*Bureau of Mines Information Circuiar/l977n00Assaying Ores, Concentrates,and BullionRevision of Information Circular 7695UNITED STATES DEPARTMENT OF THE INTERIORm 1 maut mop. Ylll(k
Information Circular 8714rAssaying Ores, Concentrates,and BullionRevision of Information Circular 7695By H. H. Heady and K. G. BroadheadUNITED STATES DEPARTMENT OF THE INTERIORCecil D. Andrus, SecretaryBUREAU OF MINES
This publication has been cataloged as follows:Heady, Howard HAssaying ores, concentrates, and bullion. Revision ofinformation circular 7695, by H. H. Heady and K. G. Brwd-head. [Washington] US. Bureau of Mines 26 p. (U.S. Bureau of Mines. Informarion circular 8714r)Includes bibliography.1. Ores-United Stares-Analysis. 2. Precious metals-UnitedSrarcs-Analysis. 3. Testing laboratories-United Srarcs. I.Broadhcad, Kenneth G., jc. aurh. 11. Title. (Series)TN23SJ71 no. 87141 622.06173U.S. Dept. of rhe 1°C. Library
CONTENTSAbstract................................................................Introduction............................................................Federal and State agencies...................................................................................Procedure for obtaining ore samplesProcedure for sampling bullion and scrap................................Description of testing techniques.......................................Chemical analysis..................................................Fire assay analysis................................................Optical emission spectrographic analysis...........................X-ray analysis.....................................................Atomic absorption analysis.........................................Neutron activation analysis........................................Bullion assay......................................................Prices and fees.........................................................References..............................................................Appendix A.--State Liaison Offices......................................Appendix B.--Commercial assay laboratories..............................
ASSAYING ORES, CONCENTRATES, AND BULLIONRevision of Information Circular 7695byH. H. Heady 1 and K. G. Broadhead2ABSTRACTThis Bureau of Mines report provides s p e c i f i c information regarding theanalysis of o r e s , concentrates, and bullion. It describes a n a l y t i c a l servicesprovided by some Federal agencies, and discusses a n a l y t i c a l techniques applica-ble t o the precious metals. The appendixes list Bureau of Mines S t a t e LiaisonOffices and c m e r c i a l assay laboratories.INTRODUCTIONSharp increases i n the world market prices of gold and s i l v e r have gen-erated a renewed i n t e r e s t i n prospecting and mining. Almost simultaneouslythere has been an upsurge of i n t e r e s t i n the platinum-group metals owing notonly t o a shortage of these metals but a l s o t o prospecting activity--partic-ularly i n the Western United States. S t i l l another f a c t o r contributing t o thebooming i n t e r e s t i n the noble metals i s the recent l e g i s l a t i o n (PublicLaw 93-373) e f f e c t i v e December 31, 1974, t h a t permits c i t i z e n s of the UnitedStates t o buy and possess gold. As a r e s u l t of t h i s s i t u a t i o n , many c i t i z e n sare seeking information and advice regarding investing, prospecting, mining,milling, r e f i n i n g , and analyzing the noble metals.This paper is a revision and updating of Information Circular 7695 (6) .3FEDERAL AND STATE AGENCIESMany mineral samples a r e sent t o Government agencies with the requestthat they be assayed or chemically analyzed. It should be emphasized t h a t -there a r e no Federal agencies, except f o r the U.S. Mints, where assays andquantitative analyses a r e made f o r t h e public.Many of the States maintain a Bureau of Mines, a Geological Survey, orsome similar organization, frequently a t a S t a t e university, where mineralslSupervisory research chemist.2Chemical engineer.3 ~ n d e r l i n e dnumbers i n parentheses r e f e r t o items i n the l i s t of referencespreceding t h e appendixes of t h i s report.
found by residents of the State w i l l be identified free of charge. Usually,a charge is made for assays. Specific t e s t s , as on clays, a r e made by someof these offices.The Federal Bureau of Mines, although it attempts t o avoid duplicationof services rendered by S t a t e agencies, i s authorized t o give advice regardingprospective markets. It does not compete with private assayers and chemists,but it w i l l accept samples sent t o i t s f i e l d laboratories, and identify themby visual o r microscopic inspection. This examination is usually s u f f i c i e n tt o indicate whether the material has cormnercial value, or a t l e a s t i f theexpense of an assay would be warranted. Except i n connection with i t s owntechnical investigations, no assays or other special t e s t s are made by theBureau of Mines. A general statement of policy regarding the ~ u r e a u sminer-alogical services t h a t are available t o the public i s included i n the FederalRegister (2).The U.S. Geological Survey and the Smithsonian I n s t i t u t i o n a l s o makemineral identifications of specimens as a public service. However, neitherof these agencies nor the Bureau of Mines w i l l provide such services on longs u i t e s of specimens submitted by mineral dealers, well d r i l l e r s , or others,when such work can be done regularly by conrmercial concerns.The U.S. Mint, Denver, Colo., provides assays of ores for gold, s i l v e r ,copper, lead, and zinc. The U.S. Mints a l s o perform assays of gold and s i l v e rbullion. The special services provided, the charges involved, and the loca-tions of U.S. Mints a r e presented i n the Code of Federal Regulations,T i t l e 31--Money and Finance, published by the Office of the Federal Register,General Services Administration. A copy of t h i s regulation can be obtainedfrom the Superintendent of Documents, U.S. Government Printing Office,Washington, D.C . 20402.PROCEDURE FOR OBTAINING ORE SAMPLESThe economic exploitation of a mineral deposit follows a more o r less s e tsequence. Invariably, the f i r s t s t e p i s identification t o determine whetherthe ore t o be mined or the mineral t o be sold i s actually what it i s thoughtt o be. An identification i s a qualitative examination designed t o giveinformation as t o what a substance may be rather than how much of it may bepresent.I f the identification shows the material t o be one of possible commercialvalue, the next s t e p is t o take a sample representative of the exposed faceo r outcrop f o r assay or quantitative chemical analysis. Preliminary considera-t i o n also should be given t o c e r t a i n economic aspects. For example, nomineral deposit, irrespective of its s i z e and grade, i s of immediate value i fit i s so inaccessible t h a t the product cannot be mined, processed, transported,and sold a t a p r o f i t on a competitive market.Sampling should always be made on a fresh surface. There a r e twosuggested ways of proceeding, of which the second i s the more r e l i a b l e .
F i r s t method: With a hamner, knock off chips of approximately equal sizea t regular intervals over the whole width of the mineral occurrence.Second method: Draw two p a r a l l e l lines 3 inches a p a r t , marking the widtht o be sampled. With a cold c h i s e l , or a moil of tempered s t e e l , cut out agroove, one-half inch or so i n depth, for the whole length between the twolines. The material thus chiseled out w i l l constitute the sample. It i s veryimportant t o carefully c o l l e c t the whole of the detached material, both chipsand dust, on a sheet of canvas, strong cotton, o r cloth.A sample thus obtained w i l l be f a i r l y representative of the mineraliza-t i o n a t the place where it was taken. I n order t o make an estimate of thevalue of a mineral deposit, i t w i l l be necessary t o repeat the samplingprocess a t regular i n t e r v a l s , about every 20 f e e t , and a t the same time,take note of the location and the length of the grooves thus made. Bag andnumber each sample separately.I f the analyses of samples taken i n t h i s manner show promise, thesucceeding steps i n the procedure a r e (1) a thorough sampling of the depositt o determine grade and tonnage available, (2) beneficiation or smelting t e s t s ,(3) a marketing survey, and (4) consideration of such engineering factors a smining methods, design of concentration or treatment plant, water and powersupply, and estimates of costs.These operations a r e usually d i f f i c u l t and expensive and should becarried out under the guidance of trained engineers. The development of aprospect from the original discovery t o a producing mine is a major under-taking t h a t requires considerable c a p i t a l and experience.Advice as t o how t o proceed with a project may be obtained from a numberof sources. Advice of a general s o r t , requiring no f i e l d work o r laboratoryt e s t i n g , can be obtained from the Bureau of Mines. (See appendix A.) Forprojects where a paid, professional consultant is needed, names and addressesmay be found i n the advertising sections of appropriate trade journals. TheDirectory of Members of the American I n s t i t u t e of Mining and MetallurgicalEngineers, 345 East 47th S t r e e t , New York 10017, l i s t s the names andaddresses of mining engineers and metallurgists available f o r consultation.For names of consultants specializing i n metallurgical and chemical problems,a useful source is the c l a s s i f i e d directory of the Association of ConsultingChemists & Chemical Engineers, 50 East 41st S t r e e t , New York.PROCEDURE FOR SAMPLING BULLION AND SCRAPThe proper sampling of bullion and/or scrap precious metals, such a selectronic, dental, o r jewelry scrap, i s very d i f f i c u l t and requires theutmost precautions. According to Bugbee (3), the principal problem encoun-tered i n sampling bars or ingots involves the irregular distribution of thevarious constituents caused by segregation when the bar freezes from themolten s t a t e . When a bar or ingot i s poured, s o l i d i f i c a t i o n begins f i r s t a tthe cooler walls of the mold, and the constituent having the highest meltingpoint s o l i d i f i e s f i r s t . The material t h a t freezes l a s t , near the upper middle
of t h e bar, i s therefore enriched i n the lowest melting point metal.Obviously, the b e s t way t o sample material of t h i s type would be while it i smolten and homogeneous. Since t h i s i s normally impossible except t o ther e f i n e r , d r i l l i n g or sawing the bar offer the b e s t alternatives. Sawing ismore laborious and destroys the continuity of the bar since i t would have t obe sawed completely through. I n d r i l l i n g the b a r , it is important t o sampleboth the ends as well as the middle and t o d r i l l e i t h e r completely throughthe bar or t o d r i l l half way through from both sides. The material removedfrom the bar must, i n turn, be carefully sampled f o r assay o r , i n s a wcases, remelted and e i t h e r sampled while molten or frozen rapidly by pouringi n t o water s o that segregation does not occur. Proper sampling of obviouslyheterogeneous metals such as i n d u s t r i a l , jewelry, o r dental scrap requirest h a t the material be melted prior t o sampling. The sampling of scrapelectronic parts consisting of c i r c u i t boards, and components such astransistors and integrated c i r c u i t s , i s a d i f f i c u l t task and requires anassay on each constituent and an estimate on t h e i r t o t a l number. It may befeasible i n some cases, such as i n sampling c i r c u i t boards, t o r o a s t the sam-ple t o remove the organic material and then analyze the ash f o r the metalvalues of i n t e r e s t .DESCRIPTION OF TESTING TECHNIQUESVarious t e s t i n g techniques are available t o the public a t commerciallaboratories, the choice of which depends on the problem t o be solved. Themost useful techniques are described t o familiarize the reader with t h e i rapplication a s well as t h e i r limitations.Chemical AnalysisA chemical analysis i s often used t o determine how much of a particularelement i s present i n a sample. Chemical analyses are normally very preciseand accurate, but they are often less sensitive and more time consuming thaninstrumental analyses. It is because of these disadvantages t h a t wet chemicaltechniques a r e usually not suitable f o r the determination of the noblemetals (gold, s i l v e r , platinum-group metals) i n ores and concentrates. I nrecent years, there has been a merging and combining of chemical and instru-mental techniques t o take advantage of the best features of both approaches. .For example, an ore sample might be put i n t o solution and separatedchemically i n t o fractions t h a t are subsequently analyzed f o r selected elementsby e i t h e r standard chemical o r atomic absorption procedures.The value of a quantitative analysis depends on how representative thesample i s of the t o t a l bulk of material t o be tested. No ore or mineraldeposit is uniform throughout; consequently, an analysis of a sample consist-ing of a single specimen or a few randomly chosen pieces of rock i s uselessi n attempting t o evaluate a potential deposit. This information can beobtained only by prescribed s c i e n t i f i c methods of sampling.
F i r e Assay AnalysisThe term " f i r e assaying" is applied t o a quantitative determinationprocedure i n which a precious metal is separated from impurities by a fusionprocess and weighed t o determine the amount of t h a t metal present i n theoriginal sample. This method is normally used f o r the determination of goldand s i l v e r i n o r e s , concentrates, and i n various metal alloys. It can a l s obe used i n conjunction with atomic absorption and spectrographic procedures(2, 12) f o r the determination of platinum and the platinum-group metals.Excellent t e x t s have been w r i t t e n on f i r e assaying by Bugbee (2)andShepard and Dietrich (10).-I n general, the procedure involves the addition of various fluxingmaterials t o the ore o r sample, which when heated t o about 1,900 F form areadily f u s i b l e homogeneous slag. Concurrent with the s l a g formation, acollecting or alloying metal, usually lead, is produced i n the molten massby reduction of p a r t of the slag mixture. The noble metals a r e reduced fromthe mass and simultaneously collected by t h e droplets and m i s t of f a l l i n g lead,forming a pool a t the bottom of the s l a g . The molten mix is poured i n t o aniron mold, and a f t e r cooling, the lead b u l l i o n containing t h e noble metalsi s physically separated from the g l a s s l i k e s l a g and treated by a processcalled cupellation. This separates the lead from t h e precious metals byoxidizing the lead, which is absorbed i n t o a special bone-ash d i s h c a l l e d acupel. The precious metals a r e l e f t a s a small bead on t h e surface of thecupel. I n an analysis f o r gold and silver, the bead i s weighed on a s p e c i a lbalance t h a t gives t h e combined weight of gold and s i l v e r i n the sample. Thebead i s then t r e a t e d with d i l u t e n i t r i c a c i d , which dissolves the s i l v e r butdoes not put any of the gold i n t o solution. The bead is then reweighed t odetermine i t s gold content. I n the analysis of platinum or the platinum-groupmetals, usually a small, known amount of s i l v e r is added before the fusionprocess. The r e s u l t i n g bead a f t e r cupellation i s then analyzed by e i t h e rspectrographic o r atomic absorption methods.Although there a r e many advantages t o the use of f i r e assay, probablythe most important is t h a t there a r e no o r e s , concentrates, or alloys t h a tcannot be analyzed by t h i s method i f it is properly performed. Furthermore,large and, consequently, more representative samples may be analyzed. I naddition, the procedure has excellent s e n s i t i v i t y , l e s s than.0.005 oz/ton ofgold may be determined, and t h e method i s s p e c i f i c f o r the noble metals. Thedetection l i m i t f o r each of the platinum group metals i s about 0.001 oz/ton,based on the analysis of an assay ton (29.2 grams) by a fire-assay-spectrographic procedure. The disadvantages a r e t h a t the technique is normallyapplied only t o the noble metals. It requires more time and therefore is morecostly than some other procedures. It a l s o requires s p e c i a l balances andfurnaces not normally found i n a chemical laboratory.Optical Emission Spectrographic AnalysisThis analysis technique is based upon the principle t h a t when a samplei s heated t o high temperature i n a n e l e c t r i c a l a r c , causing the sample t o bev o l a t i l i z e d completely, each element present i n the sample emits a unique
spectra t h a t can be used t o identify t h a t particular element. I n usualpractice, a very small amount (5 t o 50 mg) of f i n e l y pulverized ore sample(or f i l i n g s i f the sample i s metallic) i s vaporized completely, and the r e s u l t -ing spectra is recorded and used t o determine the metals present. Thisgeneral procedure can a l s o be used t o estimate the approximate concentrationof each metal detected. I f necessary, t h i s technique can be further special-ized t o permit the quantitative determination of selected elements. Thechief advantage of a spectrographic analysis i s t h a t 30 t o 50 elements canbe readily determined a t quite low concentration levels. Consequently, alarge number of samples can be surveyed rapidly t o determine t h e i r generalelemental composition. An important disadvantage is that most of the noblemetals cannot normally be detected below about 30 parts per million (about1 oz/ton) i n ores and concentrates. Another disadvantage i n applying t h i stechnique for detecting precious metals a t low concentrations i s thepossibility of misidentification due t o interferences from other elements i nthe sample. Since the usual requirement i s t o detect noble metals a t con-centration levels as low as 0.01 oz/ton, the spectrographic approach isnot recommended. More specific information on spectrographic analysis maybe gained from a good t e x t such a s the one by Aherns and Taylor (l).X-Ray AnalysisI n X-ray fluorescence analysis, the sample i s exposed t o a high-intensity gamma ray o r X-ray beam, which causes each element present i n thesample t o emit characteristic X-rays t h a t can be used t o identify therespective elements. The intensity of t h i s secondary X-radiation f r a n thesample i s a l s o d i r e c t l y proportional t o the concentration of each elementt h a t i s present. I n ordinary practice, a small amount of finely pulverizedsample is placed i n the X-ray instrument and excited by the X-ray beam.The whole range of emitted X-rays can be recorded t o determine which elementsa r e present, or X-rays emitted from a particular element can be counted andcompared with those of known standards t o determine the exact concentration.The main advantages o f t h i s X-ray fluorescence technique a r e t h a t it is simple,rapid, highly r e l i a b l e , and quite accurate providing proper calibration hasbeen achieved f o r each type of sample being analyzed. Some disadvantages a r et h a t t h i s technique i s matrix-dependent and, consequently, i t cannot be usedt o determine the metal content of o r e s , concentrates, or alloys without f i r s tbeing carefully calibrated t o handle each particular type of material.Another disadvantage is that most of the noble metals cannot be detected belowabout 50 t o 100 parts per million (2 t o 3 ozlton). Therefore, t h i s approachis not reconmended f o r the d i r e c t determination of gold, s i l v e r , o r theplatinum-group metals i n ores or concentrates. Liebhafsky, P f e i f f e r , Winslow,and Zemany (7) give an excellent discussion on the application of X-rayfluorescence analysis techniques.Another useful t o o l is X-ray diffraction (8). This technique i s basedupon the f a c t t h a t the c r y s t a l structure of any given sample causes theincident X-rays t o be diffracted i n a manner characteristic of t h a t particularmaterial. The resulting X-ray diffraction pattern i s l i k e a fingerprint f o rt h a t material, and can be used t o identify it even i n the presence of otherc r y s t a l l i n e materials. Over 20,000 different minerals, metals, and compoundshave been catalogued by t h e i r characteristic X-ray d i f f r a c t i o n patterns.
The use of t h i s catalogue simplifies t h e i d e n t i f i c a t i o n of the variouscomponents i n any c r y s t a l l i n e sample. The advantage of X-ray d i f f r a c t i o n i st h a t it t e l l s something about the composition and s t r u c t u r e . Ordinarily,X-ray d i f f r a c t i o n is not used t o make quantitative determinations. However,i n s p e c i a l cases, such a s the determination of f r e e s i l i c a i n a coal mine dustsample, it is f e a s i b l e t o make quantitative analyses.Atomic Absorption AnalysisAtomic absorption i s based on t h e f a c t t h a t a f r e e atom i s capable ofabsorbing l i g h t of the same wavelength it would normally emit. I f l i g h temitted by an element inside a s p e c i a l lamp i s passed through a gaseous cloudcontaining t h i s element i n the atomic s t a t e , then the atoms from t h i s element,and only t h i s element, w i l l absorb t h i s l i g h t . I n p r a c t i c e , the gaseouscloud is formed by aspirating a solution of the sample t o be analyzed i n t oa flame of s u f f i c i e n t temperature t o reduce the element t o i t s atomic s t a t e .The absorbance of the l i g h t from the s p e c i a l lamp by the aspirated samplesolution i s then compared with the absorbances of s u i t a b l e standards analyzedi n a similar manner. Prior t o a n a l y s i s , the sample obviously must be puti n t o solution with s u i t a b l e solvents. I n gold a n a l y s i s , t h i s can beaccomplished readily with aqua r e g i a , a mixture of n i t r i c and hydrochloricacids. For the analysis of gold and the platinum-group metals, dissolutionand d i r e c t analysis of ores or concentrates i s impractical; the very smallabsorption signal from the low levels of these metals t h a t a r e normallyencountered is masked by l i g h t s c a t t e r i n g i n the flame caused by highconcentrations of dissolved s o l i d s (4). Consequently, it is necessary t or e s o r t t o methods involving organic e x t r a c t i o n of the precious metals fromthe acid solution and analysis of these e x t r a c t s , or the use of f i r e assayt o preconcentrate the precious metals i n t o a small bead t h a t can be dissolvedand analyzed by atomic absorption. Using an acid digestion-organic e x t r a c t i o nmethod on a 1-gram sample, l e s s than 0.01 ounce of gold per ton of ore maybe measured. I f a f i r e assay preconcentration is used, the s e n s i t i v i t y canbe extended s t i l l further. Atomic absorption a n a l y s i s , when properly applied,has few disadvantages, and i t is f a s t , accurate, and economical. It hasthe advantage t h a t the equipment i s comparatively inexpensive. Furthermore,since the method may be employed f o r t h e analysis of most metals, manyt e s t i n g laboratories use t h i s technique. An excellent and comprehensive t e x ton t h i s type of analysis i s the one by Ramirez-Muiioz (2).Neutron Activation AnalysisThis method of analysis i s based on the principle t h a t when a samplei s subjected t o bombardment by neutrons, some of the s t a b l e atoms t h a t makeup the sample w i l l absorb neutrons and become radioactive. These radioactiveatoms w i l l , i n t u r n , emit gama rays the energies of which are c h a r a c t e r i s t i cof the particular elements. Using s u i t a b l e and r a t h e r sophisticatedelectronic counting equipment, these g a m rays can be detected, and theelements and amounts present i n the sample can be determined. Alternatively,t o obtain greater s e n s i t i v i t y and avoid interferences, the activated samplemay be dissolved and t h e elements of i n t e r e s t chemically separated p r i o r t obeing counted. For gold and s i l v e r , the d i r e c t electronic method has
excellent s e n s i t i v i t y , but f o r the platinum-group metals, chemical separationtechniques a r e required. This type of analysis would not normally be u t i l i z e df o r ores or concentrates. Analysis of the noble metals by t h i s method i susually limited t o r a t h e r e s o t e r i c samples, such a s moon rocks, f i l i n g s fromancient coins, and geological samples with exceedingly small and noneconomicamounts of metals present. Only small samples a r e usually i r r a d i a t e d i nnuclear r e a c t o r s , and consequently any material t h a t i s not c l e a r l y homoge-neous, such a s a gold o r e , can give erroneous r e s u l t s . Furthermore, themethod i s expensive and i s only performed commercially i n a few laboratories.Bullion AssayThe analysis of gold or s i l v e r bullion i s more complex, time consuming,and expensive than a standard f i r e assay. This i s readily understandablesince the material the sample represents is very valuable and, therefore,the analysis warrants the utmost a t t e n t i o n . Great care must be exercised i nobtaining proper samples t h a t a r e t r u l y representative of the whole material.The assay of gold and s i l v e r bullion i s expressed i n p a r t s per thousand c a l l e dfineness. For example, a gold bullion containing 99 percent gold, or 990p a r t s per thousand, is 990 fine.The assay f o r s i l v e r i n s i l v e r bullion o r gold bullion may beaccomplished e i t h e r by cupellation or by wet chemical volumetric methods.The cupellation method i s subject t o more e r r o r s , and i f accurate values a r eneeded, as i n the assay of f i n e s i l v e r bullion, the chemical procedure mustbe applied. The e r r o r s i n the cupellation assay f o r s i l v e r a r e corrected bymeans of a check or proof assay of a synthetic sample of approximately thesame weight and composition a s the b u l l i o n sample. The check and bullionsamples a r e cupelled side by s i d e , and it i s assumed t h a t the losses a sdetermined f o r the check sample a l s o apply t o the bullion. Therefore, themethod involves a preliminary assay t o determine the approximate compositionof the bullion before the check assay can be prepared. The sample s i z enormally taken i s about one-half gram. The assay of f i n e s i l v e r bullion,greater than 990 f i n e , i s normally accomplished by a wet chemical procedurec a l l e d the "Gay Lussac--U.S. Mint Method" Q). I n t h i s technique, the s i l v e rsample, about 1 gram, is accurately weighed, dissolved i n n i t r i c a c i d , andabout 99.8 percent of the s i l v e r i s precipitated with a 100-ml NaCl solutiont h a t has been previously standardized with pure s i l v e r . Subsequent m i l l i l i t e radditions of the diluted standardized NaCl solution a r e added u n t i l nofurther p r e c i p i t a t i o n occurs. A more recent refinement of t h i s method usesatomic absorption t o determine the small amount of s i l v e r remaining i n solu-t i o n a f t e r the i n i t i a l precipitation with the standardized NaCl solution.The general method of assaying gold bullion is by cupellation and partingaccompanied by check or proof assays on synthetic alloys corresponding t o thecomposition and weight of the b u l l i o n (2, -10). Therefore, the method usuallyrequires a preliminary assay t o obtain a n approximate analysis. As i n thecase of s i l v e r bullion a n a l y s i s , t h e check and b u l l i o n samples a r e cupelleds i d e by s i d e , and any loss or gain i n t h e check sample, which i s called thesurcharge, i s applied t o the b u l l i o n sample. I n the parting process, whichseparates the s i l v e r from the gold, the silver-gold r a t i o must be kept between
2 t o 4 parts s i l v e r t o 1 p a r t gold, otherwise proper parting w i l l not beachieved. Consequently, s i l v e r must normally be added t o both the bullionand proof sample. The r e s u l t i n g bead from the cupellation must be r o l l e dvery t h i n and parting procedure must be c a r e f u l l y standardized. I n boththe s i l v e r and gold bullion assay, r e s u l t s a r e obtained on duplicate samples.PRICES AND FEESThe trade generally recognizes three q u a l i t i e s of work. The f i r s t andlowest priced analysis i s designated by such terms a s routine, engineerssurvey, and preliminary. A higher priced, more c a r e f u l analysis i s c a l l e dcontrol, and t h i r d and most expensive is called umpire. Unfortunately,there i s no way of s e t t i n g up standards of q u a l i t y on the basis of accuracybecause sane elements, such as iron or copper, can be determined i n theusual samples with l i t t l e e f f o r t t o a high degree of accuracy, whereas othersrequire time-consuming procedures and great s k i l l , i n s p i t e of which accuracyof r e s u l t s i s only f a i r .The price ranges l i s t e d a r e t y p i c a l of the prices being quoted by conrmer-c i a 1 laboratories a s of January 1, 1977, f o r routine analyses. The l i s t e dvalues a r e f o r s i n g l e , f i n e l y ground samples. An e x t r a charge of $ 1 t o $5per sample i s assessed i f the sample has t o be prepared f o r analysis.Discounts a r e usually granted i f many samples of the same type a r e submitteda t one time.Atomic:::;1abs;;ionGold ....................... $4- $8 $3-$7Silver.. ................... 4- 8Gold and s i l v e r . . . . . . . . ....Platinum ................... 20-l70 25-35Higher prices a r e charged f o r the assay of the r i c h e r samples, such a sbullion, sweepings, and jewelry. Control and umpire analyses cost two t othree times t h e price of routine analyses.A q u a l i t a t i v e spectrographic analysis t o determine the general elementalcomposition costs about $15 t o $30 per sample. An X-ray d i f f r a c t i o n analysist o determine the mineral composition of a sample costs about $30 t o $50.Most of the c m o n metals i n o r e s , concentrates, and alloys can bedetermined with reasonable accuracy by atomic absorption. The cost is $1.50t o $3 f o r the f i r s t element, plus about $ 1 t o $2 f o r each succeeding elementi n the same sample. S m of the metals t h a t can be determined by t h i s tech-nique a r e bismuth, cadmium, chromium, c o b a l t , copper, i r o n , lead, manganese,molybdenum, nickel, t i n , and zinc.
A few laboratories perform mineralogical services. the c o s t of whichvaries with the type of a n a l y t i c a l work required . Typical services andestimated costs a r e as follows:Petrographic and mineralogical examination per hour ...... $10Thin sections ................................pe r sample .. $4- 14Polished sections ................................d o . . . 4- 15Grain mounts .....................................do ...... 4- 10P a r t i c l e s i z e d i s t r i b u t i o n .......................do ...... 25- 35Specific gravity .................................do . 4- 6
REFERENCESAherns , L. H. , and S. R. Taylor. Spectrochemical Analysis. Addison-Wesley Publishing Co., Inc., Reading, Mass., 2d ed., 1961, 429 pp.Broadhead, K. G . , B. C. Piper, and H. H. Heady. Fire Assay-EmissionSpectrographic Determination of Iridium, Ruthenium, and Osmium. Appl.Spectr., v. 26, No. 4 , 1972, pp. 461-467.Bugbee, E. E. A Textbook of F i r e Assaying. John Wiley & Sons, Inc. ,New York, 3d ed., 1940, p. 221.E l l i o t t , E .V. , and K. R. Stever. Problems i n Determining the NobleMetals i n Ores. Atomic Absorption Newsletter, v. 12, No. 3 , 1973,pp. 60-62.Furman, N. H. (ed.). Standard Methods of Chemical Analysis. D. VanNostrand Co. Inc., Princeton, N.J., 6th ed., 1966, pp. 985-988.Klahold, B. R. Laboratories That Make Fire Assays, Analyses, and Testsof Ores, Minerals, Metals, and Other Inorganic Substances. BuMinesI C 7695, 1954, 20 pp.Liebhafsky, H. A . , H. G . P f e i f f e r , E. H. Winslow, and P. D. Zemany.X-Ray Absorption and Emission i n Analytical Chemistry. John Wiley& Sons, Inc., New York, 1960, 357 pp.Nuffield, E. W. X-Ray Diffraction Methods. John Wiley & Sons, Inc.,New York, 1966, 409 pp.Ramirez-Muibs, J. Atomic Absorption Spectroscopy. Elsevier PublishingCo. , New York, 1968, 495 pp.Shepard, 0. C . , and W. F. Dietrich. Fire Assaying. McGraw-Hill BookCo. , Inc. , New York, 1940, 277 pp.U.S. Bureau of Mines. Policy Statement on Mineralogical Services.Federal Register, v. 40, No. 134, July 11, 1975, p. 29308.Whitehead, A. B . , and H. H. Heady. Fire-Assay Emission SpectrographicMethod for Platinum, Palladium, Rhodium, and Gold. Appl. Spectr.,v. 24, No. 2 , 1970, pp. 225-228.
APFENDIX A.--STATE LIAISON OFFICESLocal InformationThe U.S. Department of the I n t e r i o r has established, through its Bureauof Mines, S t a t e Liaison Officers t o represent each of the States and t e r r i -t o r i e s . The primary mission of these Officers i s t o conduct the Bureausbusiness t h a t can best be accomplished a t the S t a t e and local levels, t oinsure participation of appropriate organizations within the S t a t e i n actionsof mutual concern, and t o serve as a Federal point of contact. The LiaisonOfficers a r e familiar with the mining and metallurgical a c t i v i t i e s i n t h e i rparticular geographical areas. Accordingly, they are available t o provideinformation and advice t o private citizens and people i n industry who a r einterested i n prospecting, mining, milling, refining, and analyzing preciousmetals. The attached l i s t of S t a t e Liaison Officers i s provided as a matterof general i n t e r e s t and service t o the public.Bureau of Mines, U.S. Department of the I n t e r i o r ,Liaison Program Office DirectoryAlabamaState Liaison OfficeArkansasS t a t e Liaison OfficeBureau of Mines Bureau of MinesU.S. Department of the I n t e r i o r U.S. Department of the I n t e r i o rP.O. Box L Room 3331, Federal Office Bldg.University, Ala. 35486 L i t t l e Rock, Ark. 72201(205) 758-0491 (501) 378-5965AlaskaS t a t e Liaison OfficeCaliforniaS t a t e Liaison OfficeBureau of Mines Bureau of MinesU.S. Department of the I n t e r i o r U.S. Department of the I n t e r i o rRoom G-81, Federal Bldg. Room 3046Anchorage, Alaska 99501 650 Capitol Mall(206) 442-0151 Sacramento, Calif. 95814(916) 440-2417ArizonaS t a t e Liaison OfficeBureau of MinesColoradoS t a t e Liaison OfficeU.S. Department of the I n t e r i o r Bureau of MinesRoom 1012 U.S. Department of the I n t e r i o r2721 North Central Ave. Room 820, Bldg. 67Phoenix, Ariz . 85004 Denver Federal Center(602) 261-3357 Denver, Colo. 80225(303) 234-4205
ConnecticutSee New HampshireDelawareSee MarylandFloridaState Liaison OfficeBureau of MinesU.S. Department of the InteriorRoom 204547 North Monroe S t .Tallahassee, Fla. 32301(904) 222-6218GeorgiaState Liaison OfficeBureau of MinesU.S. Department of the InteriorRoom 43119 Martin Luther King, Jr., D r . , SWAtlanta, Ca. 30334(404) 221-6204HawaiiSee CaliforniaIdahoState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 2034620 Overland Rd.Boise, Idaho 83705(208) 384-1084I l l i n o i sState Liaison OfficeBureau of MinesU.6. Depsrtmnt of the I n t e r i o rRoom 102, Jefferson West No. 1525 W . Jefferson St.Springfield, Ill. 62702(217) 525-4368IndianaS t a t e Liaison OfficeBureau of MinesU.S. Department of the InteriorRoom 113Seventh and College Sts.Bloomington, Ind. 47401(812) 339-6139Iowa-See MissouriKansasS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rSuite 220, Federal Bldg./U.S. Courthouse444 S.E. QuincyTopeka, Kans. 66603(913) 295-2520KentuckyS t a t e Liaison OfficeBureau of MinesU.S. Department of the InteriorRoom 269John C. Watts Federal Bldg.330 West BroadwayFrankfort, Ky . 40601(502) 875-4120LouisianaState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 119, Federal Bldg. andCourthouse707 Florida S t .Baton Rouge, La. 70801(504) 387-0181, ext. 374Maine-State Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rP.O. Box 228Augusta, Maine 04330(207) 622-6171, e x t . 292
MarylandS t a t e Liaison OfficeMontanaState Liaison Of £iceBureau of MinesU.S. Department of the I n t e r i o rColumbia PlazaRoom 9072401 E S t . , N.W.Washington, D.C. 20241(202) 634-1272MassachusettsSee New HampshireMichiganS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 1121, C-rce Center Bldg.300 Capitol S t .Lansing, Mich. 48933(517) 372-1910, ext. 681MinnesotaS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rP.O. Box 1660Twin C i t i e s , Minn. 55111(612) 725-4535MississippiS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 408, 301 Bldg.301 North Lamar S t .Jackson, M i s s . 39202(601) 969-4208MissouriS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rP.O. Box 1187Rolla, Mo. 65401(314) 364-5555Bureau of MinesU.S. Department of the I n t e r i o r636 North LoganHelena, Mont. 59601(406) 449-5297NebraskaSee KansasNevadaState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 306, Post Office Bldg.705 North Plaza S t .Carson City, Nev. 89701(702) 882-9380New HampshireS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rPost Office and Federal Bldg.Newmarket, N .H. 03857(603) 659-3101New JerseySee PennsylvaniaNew MexicoState Liaison OfficeBureau of MinesU.S. Department of the InteriorRoom 104, U.S. Courthouse/Federal Bldg .Santa Fe, N. Mex. 87501(505) 988-6624New YorkS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rSuite 2031659 Central Ave.Albany, N.Y. 12205(518) 869-9536
North CarolinaState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rP.O. Box 2828Raleigh, N.C. 27602(919) 755-4166North DakotaState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 7 , 207 E. BroadwayBismarck, N. Dak. 58501(701) 255-4011, ext. 378Ohio-See IndianaOklahomaState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o r168 Post Office Bldg.N.W. Third S t .Oklahoma City, Okla. 73102(405) 231-4521OregonState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rSuite 7 , Standard Insurance Bldg.475 Cottage S t . , NESalem, Oreg. 97301(503) 399-5755PennsylvaniaState Liaison OfficeBureau of MinesU.S. Departmnt of the I n t e r i o rP.O. Box 783Federal Square StationHarrisburg, Pa. 17108(717) 782-4474Puerto RicoSee FloridaSouth CarolinaS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o r403 Columbia Bldg.Main and Gervais Sts.Columbia, S.C. 29201(803) 765-5561South DakotaState Liaison OfficeBureau of MinesU. S. Department of the I n t e r i o rRoom 261, Federal Bldg.,U.S. Courthouse515 Ninth St.Rapid City, S. Dak. 57701(605) 342-1950TennesseeState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o r1109 Parkway Towers404 James Robertson ParkwayNashville, Tenn. 37219(615) 749-7254TexasS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 782, Federal Bldg.Austin, Tex. 78701(512) 397-5781Utah-S t a t e Liaison Of £iceBureau of MinesU.S. Department1600 East F i r s tS a l t Lake City,(801) 524-5383of the InteriorSouth S t .Utah 84112VermontSee New HampshireVirginiaSee North CarolinaRhode IslandSee New Hampshire
WashingtonState Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 205Evergreen Plaza Bldg.711 S. Capitol WayOlympia, Wash. 98501(206) 753-9445WisconsinSee MinnesotaWyomingS t a t e Liaison OfficeBureau of MinesU.S. Department of the I n t e r i o rP.O. Box 1796Cheyenne, Wyo. 82001(307) 778-2220, e x t . 2481West VirginiaState Liaison OfficeBureau of MinesU.S. Department of the InteriorP.O. Box 428Charleston, W. Va. 25322(304) 343-6181, ext. 443Headquarters OfficeWashington, D.C.Chief, State Liaison Program OfficeBureau of MinesU.S. Department of the I n t e r i o rRoom 901, Columbia Plaza2401 E S t . , N.W.Washington, D .C . 20241(202) 634-1272
APPENDIX B.--COMMERCIAL ASSAY LABORATORIESThe following l i s t i n g of assay laboratories, arranged alphabetically byS t a t e , is compiled as a public service. This l i s t i n g does not necessarilyinclude every conunercial laboratory i n each S t a t e , nor does the Bureau ofMines vouch f o r or r e c m n d these laboratories w e r any others.AlabamaSouthern Testing Laboratories129 West v a l l e y U ~ v e .Birmingham, Ala . 35209Vester J. Thompson, Jr., Inc.Box 9253Mobile, Ala. 36609AlaskaAlaska Minerals and MaterialsLaboratory3944 Spenard Rd.Anchorage, Alaska 99503Alaska Testlab4040 B St.Anchorage, Alaska 99503Chemical & Geological Laboratoriesof Alaska, Inc.P.O. Box 4-1276Anchorage, Alaska 99509Resource Associates of Alaska, Inc.3230 Airport Rd.Fairbanks, Alaska 99701ArizonaAmerican Analvtical & ResearchLaboratories3441 East Milber S t .Tucson, Ariz. 85714Arizona Testing Laboratories815 West MadisonPhoenix, Ariz . 85007Iron King Assay OfficeIron King MineP.O. Box 14Humbolt, Ariz . 86329Jacobs Assay Office1435 South 10th Ave.Tucson, Ariz. 85713Rochin Assay Office Inc.P.O. Box 1323Douglas, Ariz. 85607Skyline Labs Inc.Hawley & Hawley Division1700 West Grant Rd.Tucson, Ariz. 85705Southwestern Assayers &Chemists , Inc .710 East Evans Blvd.Tucson, Ariz. 85713Valley Assay Office1010 LemonTempe, Ariz. 85281ArkansasNoneCaliforniaAIMS, Inc.1360 Bayport Ave.San Carlos, Calif. 94070Abbot A. Hanks , Inc .115 Indiana S t .San Francisco, Calif. 94107Caltest Analytical Laboratories20 McDonnelSonama, Calif. 95476Clarkson Laboratory & Supply, Inc.1144 30th S t .San Diego, Calif. 92102
Robert E . Craig & CompanyP.O. Box 577Sun Valley, Calif. 91352Eisenhauer Laboratoriesl l l O A East Edna PI.Covina , Calif. 91724GMG Assay Office432 West Main S t .Quincy , Calif. 95971Heavy Metals Laboratories1415 Colorado S t .Santa Monica, Calif. 90404John D. HessTesting Corp.356 East Main St.E l Centro, Calif. 92243Humel & Christianson ConsultingEngineers102 East AlisoOjai, Calif. 93023J & J Smelting & Refining Corp.17474 CatalpaP.O. Box 727Hesperia, Calif. 92345Kems14039 East Don J u l i o Rd.La Puente, C a l i f . 91747Metallurgical Laboratories, Inc.1142 Howard S t .San Francisco, Calif. 94103Miles D. Rombough Laboratories3069 Del Paso Blvd.Sacramento, C a l i f . 95815Minerals Engineering417 South H i l l St.Los Angeles , Calif.Morse Laboratories1525 Fulton Ave.Sacramento, Calif.Room 10999001395825Ralph E. Pray, D.Sc.Mining & Metallurgy ResearchLaboratories40 North Sycamore Ave.Pasadena, Calif. 91107Quality Control Laboratories2606 North DurfeeE l Monte, Calif. 91732Reed Engineering1140 North Lemon S t .Orange, Calif. 92667San Joaquin Research Laboratories2253 South E l DoradoStockton, Calif. 95206Twining Laboratories, Inc.2527 Fresno St.Fresno, Calif. 93721Twining Laboratories of So. C a l i f . ,Inc .3310 Airport WayLong Beach, Calif. 90801Wilkinson Assays9491 S i e r r a Ave.Fontana, Calif. 92335ColoradoAccu-Labs Research, Inc.11485 West 48th Ave.Golden, Colo. 80401Alan D. Breese, Sr.1947 South Decatur S t .Denver, Colo. 80219Brown Laboratory2263 BroadwayGrand Junction, Colo. 81501CDC Associates, Inc.5401 Western Ave.Boulder, Colo. 80301Colorado Analytical Laboratory240 South MainBrighton, Colo. 80601
Colorado Assaying Company2244 BroadwayDenver, Colo . 80205Colorado School of Mines ResearchI n s t i t u t eP.O. Box 112Golden, Colo. 80401Coors Spectro-Chemical LaboratoryDivision of Coors Porcelain Co.600 NinthGolden, Colo. 80401Ernest Engineering Co.734 East Second Ave.Durango, Colo. 81301Fluo-X-Spec Analytical Laboratory718 Sherman S t . (rear)Denver, Colo. 80203G X Labs, Inc.16948 South Golden Rd.Golden, Colo. 80401Grand Junction Laboratories439 North Ave.Grand Junction, Colo. 81501Thomas E. Hancock120 South WalnutHayden, Colo. 81639Hazen Research, Inc .4601 Indiana S t .Golden, Colo. 80401Mile High PlacersP.O. Box 483Golden, Colo. 80410Minerals Assay Laboratory549 Noland Ave .Grand Junction, Colo. 81501Natural Resources Laboratory1100 SinnnsLakewood, Colo .Mailing address:P.O. Box 702Edgemont BranchGolden, Colo. 80401Herbert M. Ochs81 South E l a t i S t .Denver, Colo. 80223Charles 0. Parker & Co.William Bealer, Owner2114 Curtis St.Denver, Colo. 80205Root and NortonWest Animas ValleyDurango , Colo . 81301Root and Simpson, Inc.1310 East 17th Ave.Denver, Colo. 80218Skyline Labs, Inc.12090 West 50th PI.Wheatridge, Colo. 80033Specomp Services, Inc .917 Lincoln Ave.Steamboat Springs, Colo. 80477George Treder Assayer1413 Idaho SpringsIdaho Springs, Colo. 80452ConnecticutYork Research Corp.1 Research D r .Stamford, Conn. 06904DelawareBrandt Associates Inc.50 Blue Hen D r .Newark, Del. 19713Lehight Testing Laboratories, Inc.P.O. Box 1241Wilmington, Del. 19898FloridaTechnical Services Inc.P.O. Box 52329Jacksonville, Fla . 32207Thornton Labs, Inc .1145 East Cass S t .Tampa, Fla. 33601
GeorgiaDunn Laboratories, Inc.717 Edgehill Ave. , NWAtlanta, Ga. 30318Law & Company635 Angier Ave. , NEAtlanta, Ga. 30308McMillan Research1221 Barclay Circle, SEMarietta, Ga. 30060Metallurgical Engineers of Atlanta3480 Oakcliff Rd.Doraville , Ga. 30340HawaiiNoneIdahoBoise Assayers & Metallurgy1519 MainBoise, Idaho 83706Idaho Assaying & Metallurgy707 North 27thBoise, Idaho 83702Peter Mack166 KingWallace, Idaho 83873Silver Valley Laboratory308 North TaylorOsburn, Idaho 83849I l l i n o i sCharles C. Kawin Company2671 GardnerBroadview, Ill. 60153Chicago Spectro ServicesLaboratories, Inc .4846 South KedzieChicago, Ill. 60632Commercial Testing and EngineeringCompany228 North LaSalleChicago, Ill. 60601Factory Standards Laboratory, Inc.416 North S t a t e S t .Chicago, 111. 60610Pittsburgh Testing Laboratory4418 RooseveltHillside, Ill. 60612Robert W. Hunt Company810 South ClintonChicago, Ill. 60607S c i e n t i f i c Control Laboratories,Inc .3136 South KolinChicago, Ill. 60623Taussig Metallurgical Associates,Inc .6955 North HamlinChicago, Ill. 60645IndianaATEC Associates of Indiana5150 East 65th S t .Indianapolis, Ind. 462200 A Laboratories, Inc.1437 Sadlier Circle, West DriveIndianapolis, Ind. 46239Sherry John M. Laboratories2112 Kilgore Ave.Muncie , Ind . 47304Iowa-Analytical and Testing Laboratories7004 CarpenterDes Moines, Iowa 50311Patzig Testing Labs, Inc.2215 IngersollDes Moines, Iowa 50311Twin City Testing and EngineeringLabs, Inc .529 LoganWaterloo, Iowa 50703
KansasArrow Laboratories, Inc.123 W. 12thWichita, Kans . 67201Means Laboratories, Inc.419 N. HandleyWichita, Kans . 67213Topeka Testing Laboratories101 N. KansasTopeka, Kans. 66603KentuckyFrazier s LaboratoryMarion, Ky. 42064LouisianaGulf South Research I n s t i t u t e7700 GSRI Ave.Baton Rouge, La. 70808Hydro-Chem Analytical1020 Florida S t .Baton Rouge, La. 70802Kem-Tech Labs16550 Highland Rd.Baton Rouge, La. 70808Shilstone Testing Lab, Inc.814 Conti S t .New Orleans, La. 70112MaineJohn S. Cunnnings , Inc .Bangor International AirportBangor, Maine 04401MarylandPenniman and B r m e , Inc .6252 Falls Rd.Baltimore Md. 21209MassachusettsArnold Green Testing Laboratories, Inc.East Natick 1ndustrIal Park6 Huron D r .Natick, Mass. 01760Arnold Green Testing Laboratories, Inc.2 Millbury St.Auburn, Mass. 01501Arnold Green Testing Laboratories, Inc.98 Paris S t .Everett, Mass. 02149Arnold Green Testing Laboratories, Inc.Springfield, Mass. 01104J. Dirates & Co., Inc.Notre Dame St.Westfield, Mass. 01085Eastern Smelting & Refining Co.37 Bubier St.Lynn, Mass. 01903Skinner & ShemanNew England Laboratories227 California St.Newton, Mass. 02195MichiganDetroit Testing Laboratory-8720 NorthendOak Park, Mich. 48237Michigan Technological UniversityI n s t i t u t e of Mineral ResearchHoughton, Mich. 49931MinnesotaLerch Brothers, Inc.P.O. Box 8Hibbing , Minn. 55746Strasburger and Siege11403 Eutaw PI.Baltimore, Md. 21217
MississippiBrown-Agee Laboratories ofMississippi879 Foley St.Jackson, Miss. 39202Environmental Protection Systems106 Upton D r .Jackson, Miss. 39209Micro-Methods , Inc .5106 Telephone Rd.Pascagoula , Miss. 39567Mississippi State Chemical LabP.O. Box 2198Mississippi State, Miss. 39762Southern Technical Services, Inc.1627 Westhaven Blvd.Jackson, Miss. 39209MissouriBruce Williams Laboratories620 Joplin S t .Joplin, Mo. 64801General Testing Laboratories1517 WalnutKansas City, Mo. 64108Industrial Testing Laboratories2350 South Seventh Blvd.S t . Louis, Mo. 63104S t . Louis Testing Laboratories2810 Clark Ave.S t . Louis, Mo. 63103MontanaButte Minerals LaboratoriesP.O. Box 3867600 East AluminumButte, Mont . 59701Frontier LaboratoriesP.O. Box 159Melrose , Mont . 59743Northern Testing Laboratories, IncP.O. Box 411600 South 25th St.Billings, Mont. 59103Western LaboratoriesP.O. Box 5373131 Airport Rd.Helena, Mont. 59601Yapuncich, Sanderson & BrownLaboratories13 North 32dBillings, Mont. 59101NebraskaHarris Laboratories. Inc.624 Peach St.Lincoln, Neb. 68502Nebraska Testing Laboratories4453 South 67th St.Omaha, Neb. 68117Omaha Testing Laboratories2917 DouglasOmaha, Neb. 68102NevadaHumboldt Geochemical Lab744 South 5thElko, Nev. 89801Humboldt LaboratoriesGrass Valley Rd.Winnemucca , Nev. 89445Nevada Assay Office5800 Reno HighwayFallon, Nev. 89406Foundation & Materials Consultants, Nevada Testing Laboratories LTDInc . 300 Boston Ave.839 Front S t . Las Vegas, Nev. 89104Helena, Mont. 59601
Rocky Mountain Geochemical Corp. Silver City Testing Laboratories, Inc.840 Greg 1024 Hudson St.Sparks, Nev. 89431 Silver City, N. Mex. 88061Edward S. Shedd939 West RobinsonCarson City, Nev. 89701Silver State Minerals Testing Lab6274 East Charleston Blvd.Las Vegas, Nev. 89122Weidemans Mining Laboratory3160 Deer Run Rd.Carson City, Nev. 89701New HampshireNoneNew JerseyInternational Testing Labs580 Market S t .Newark, N. J. 07105Ledoux & Company359 Alfred Ave.Teaneck, N . J . 07666Standard Testing Labs309 Cortlandt S t .Belleville, N.J. 07109U.S. Testing Co., Inc.1415 Park Ave .Hoboken, N.J. 07030New MexicoAlbuquerque Assay Laboratory4115 Silver Ave., SEAlbuquerque, N. Mex. 87108Grants Assay Lab1400 West Santa Fe Ave.Grants, N. Mex. 87020Martin and Carlisle ChemicalLaboratory715 San Mateo Blvd., NEAlbuquerque, N. Mex. 87108New YorkHarmnerschlae. Moe Inc .158 Canal s;.New York, N.Y. 10013Hoover & Strong Inc.119 West Tupper S t .Buffalo, N.Y. 14201Pitkin Lucius Inc.50 Hudson St.New York. N.Y. 10013Rodman & Yaruss Refining Co. Inc.17 West 47th St.New York, N.Y. 10036North CarolinaFroehling & Robertson, Inc.P.O. Box 2058Asheville , N.C. 28802Law Engineering Testing Co.P.O. Box 18288Raleigh, N.C. 27609Southern Testing and ResearchLaboratoriesP.O. Box 350Wilson, N.C. 27893North DakotaNoneOhio-CTL Eneineerine. Inc.2860 ~YsherR ~ TColumbus, Ohio 43204Crobaugh Laboratories3800 Perkins Ave.Cleveland, Ohio 44114National Spectrographic Laboratories,Inc .19500 South MilesCleveland, Ohio 44128
Wadsworth Testing LaboratoryP.O. Box 2081600 Fourth S t . , SECanton, Ohio 44701OklahomaRockwell InternationalTulsa DivisionAnalytical Laboratories2000 N. Memorial D r .Tulsa, Okla. 74115Southwell Labs1838 S.W. 13thOklahoma City, Okla. 73108United States Testing Co., Inc.1341 N. 108 East Ave.Tulsa, Okla. 74116OregonDepartmnt of Geology and MineralIndustries1069 State Office Bldg.Portland, Oreg. 97201Lawre L. Hoagland7018 SE 17th S t .Portland, Oreg. 97202Montana Assay Office610 SW Second S t .Portland, Oreg. 97201PennsylvaniaAllentown Testing Lab. Inc.754 E . Fairview St.Bethlehem, Pa. 18108Ambric Testing Labs4041 Ridge Ave.Philadelphia, Pa. 19129Booth Garret Blair180 S. Main S t .Ambler, Pa. 19002General Testing Labs. Inc.241 S. JeffersonAllentown, Pa. 18102Materials Consultants and Laboratories,Inc .1567 Old Abers Creek Rd.Monroevill e , Pa. 15146McCreath Labs. Inc.236 Liberty Ave.Harrisburg, Pa. 17101Pittsburgh Testing Laboratory850 PoplarPittsburgh, Pa. 15220Smith Rudy & Co.20 N. 3d S t .Philadelphia, Pa. 19109Spectrochemical Laboratories, Inc.8350 Frankstown Rd.Pittsburgh, Pa. 15221Rhode IslandArnold Greene Testing Laboratories, Inc.15 Bellows S t .Warwick, R.I. 02888South CarolinaCommonwealth Laboratory, Inc .112 Greenacre Rd.Greenville , S.C. 29607Environmental Analytics , IncP.O. Box 21427Columbia, S.C. 29221I n d u s t r i a l NDT Co. Inc.3409 S p r u i l l Ave.Charleston, S .C. 29405South DakotaWhitewood AssayersBox 299Whitewood, S. Dak. 57793Conwell E. L. & Co.2024 Arch S t .Philadelphia, Pa. 19103
TennesseeAtek Labs, Inc .P.O. Box 38Corryton, Tenn. 37721Environmental Science & Engineering,Inc .Mays Chapel Rd.M t . J u l i e t , Tenn. 37122Steward Laboratories, Inc .5815 Middlebrook PikeKnoxville, Tenn. 37921Technical Laboratories, Inc.515 Cherokee Blvd.Chattanooga, Tenn. 37405TexasDickinson Laboratories201 North ClarkE l Paso, Tex. 79905Western Weighers, Subsidiary ofHawley & HawleyAssayers & Chemists, Inc.P.O. Box 3471E l Paso, Tex. 79923Utah-American Chemical and ResearchLaboratories32 East 3335 SouthS a l t Lake City, Utah 84115Chemical and Mineralogical Services445 West 2700 SouthS a l t Lake C i t y , Utah 84115Crismon and Nichols440 South 500 WestS a l t Lake City, Utah 84101Material Research, Inc.1380 South West Temple S t .S a l t Lake City, Utah 84115Rocky Mountain Geochemical Corp.1323 West 7900 SouthWest Jordan, Utah 84084Rogers Research and Analysis, Inc68 South Main S t .S a l t Lake City, Utah 84101Tay Con Laboratories2040 Fortune Rd.S a l t Lake City, Utah 84104Union Assay Office , Inc .269 Brooklyn Ave .S a l t Lake City, Utah 84101Ute Research Laboratories40 North 400 WestS a l t Lake City, Utah 84116VermontNoneVirginiaComnercial Testing & Ennineerine: Co.- -1825-31 Lindsay ~ c e .Norfolk, Va. 23504Froehling & Robertson, Inc.P.O. Box 27524Richmond, Va. 23261Law Engineering Testing Co.P.O. Drawer QQMcLean, Va. 22101Penniman 6 Browne , Inc .1725 Arlington Rd.Richmond, Va. 23230Washington Testing Inc.2930 Eskridge Rd.Fairfax, Va. 22030WashingtonBennetts Chemical Laboratory. Inc .- .901 South Ninth S t .Tacoma, Wash. 98405J. M. Knisely Engineering Corp.5807 Fourth Ave., SouthP.O. Box 3724S e a t t l e , Wash. 98124
Laucks Testing Laboratories, Inc.1008 Western Ave .S e a t t l e , Wash. 98104Rocky Mountain Geochemical Corp.6319 North Helena S t .Spokane, Wash. 99207Tacoma Assay Office518 Security Bldg.Tacoma, Wash. 98402Technical Service LaboratoriesNorth 1003 Washington S t .Spokane, Wash. 99201West VirginiaCnmnercial Testing & Engineering Co.626 Broad St.Charleston, W. Va. 25323WisconsinNoneWyomingChemical and Geoloaical Laboratories-420 W. 1st S t .Casper, Wyo. 82601Natural Resources Research I n s t i t u t eCollege of EngineeringUniversity of WyomingBox 3038, University StationLaramie, Wyo. 82070U.S. GOVERNMENT PRINTING OFFICE: 1977-703-001182