This document provides a guide to minerals for practical prospectors. It outlines five main topics: 1) rock-forming minerals, 2) metallic ores, 3) non-metallic ores, 4) industrial minerals, and 5) gem minerals. For each mineral type, specific examples are given and their key identifying characteristics are described such as color, crystal structure, hardness, and typical geological environments. The goal is to enable identification of economically important minerals in the field.

1. [PRACTICAL PROSPECTOR'S GUIDE TO MINERALS] October 3, 2012
PRACTICAL PROSPECTOR'S GUIDE TO
MINERALS
By
Prof. Dr. Hassan Z. Harraz
Geology Department
Faculty Sciences, Tanta University-Egypt
hharraz2006@yahoo.com
Outline
Topic 1:Rock-Forming Minerals
Topic 2:Ores (Metallic)
Topic 3:Ores (NON-Metallic)
Topic 4:Industrial Minerals
Topic 5:Gem Minerals
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2. [PRACTICAL PROSPECTOR'S GUIDE TO MINERALS] October 3, 2012
PRACTICAL PROSPECTOR'S GUIDE TO
MINERALS
I- Rock-Forming Minerals
Quartz
 Most common mineral species
 Vitreous luster; conchoidal fracture; hexagonal, prismatic crystals are
diagnostic
 Many color varieties: amethyst, smoky, rose, citrine
 Uses: glass manufacture, abrasive, flux, optical instruments,
electronics
Feldspar Group
Potassium feldspars: microcline, orthoclase, sanidine
 blocky crystals, often show perthitic texture (especially microcline)
Plagioclase feldspars: albite – anorthite series
 range from white to black
 often show play of colors (labradorescence)
 striations on cleavage surface (albite twinning)
Mica Group
Muscovite (white mica)
Biotite (black mica)
Phlogopite (brown mica)
Sericite (brown to buff mica)
Lepidolite (purple mica)
 lithium-rich pegmatites
 micaceous cleavage, elastic nature of plates and hardness distinguish
micas from all other sheet-like minerals such as talc, gypsum and
brucite
Pyroxene Group
 Generally green to black (except spodumene, which can be white,
yellowish, pink or green).
 2 good to perfect cleavages at nearly right angles (chief distinguishing
 characteristic between pyroxenes and amphiboles).
 Pyroxenes are common in mafic to ultramafic rocks and in skarns
 Emerald-green diopside (chrome-diopside) is a diamond indicator
mineral
 Spodumene is a lithium pyroxene found in rare-element pegmatites
 Jadeite is one of the "true" jades and is a pyroxene
Amphibole Group
• Generally green to black (some, like tremolite, are white)
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3. [PRACTICAL PROSPECTOR'S GUIDE TO MINERALS] October 3, 2012
 2 good to perfect cleavages at 56 and 124 degrees (chief
distinguishing
 characteristic between amphiboles and pyroxenes).
 BC jade is "nephrite", a variety actinolite, and is considered a "true"
jade.
 amphiboles are common in skarns and in fairly high-grade
metamorphic rocks.
Garnet Group
Almandine (iron – aluminum garnet)
 generally red
 found in schists
Pyrope (magnesium – aluminum garnet)
 generally red
 diamond indicator mineral (kimberlites, lamprophyres)
Spessartine (manganese – aluminum garnet)
 red to orange
 most often in rare-element pegmatites
Grossular (calcium – aluminum garnet)
 brown, green, red, yellow
 often found in skarns
 gem brown variety known as "hessonite"
Andradite (calcium – iron garnet)
 brown, green, red, yellow, black
 often found in skarns
 gem green variety could be "demantoid"
 titaniferous variety (black) is known as "melanite"
Uvarovite (calcium – chromium garnet)
 chrome green
 associated with altered ultramafic rocks.
Serpentine Group
 varied green color, greasy luster, often fibrous (or splintery)
Olivine
 vitreous luster, conchoidal fracture, green color, presence in basalt as
nodules
Carbonate Group
Calcite
 3 cleavages not at right angles
 fizzes readily with weak acid
Siderite
 typical carbonate cleavage
 light to dark brown
Dolomite
 curved, rhombohedral crystals
 white, pink, gray
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4. [PRACTICAL PROSPECTOR'S GUIDE TO MINERALS] October 3, 2012
II- Ores (Metallic)
A. Gold
B. Platinum Group Elements:
 Platinum, Palladium, Iridium, Osmium
 placer deposits, ultramafic rocks
C. Native Silver
 wires in pockets, hackly fracture, tarnishes black
 often as an impurity in galena
D. Sulfosalts
 Pyrargyrite/Proustite (ruby silvers)
 Stephanite
 Tetrahedrite
E. Native Copper (100% Cu)
 often in basalt; sometimes in oxidized zone; hackly fracture,
copper color
F. Chalcopyrite (35% Cu)
 no cleavage, greenish-black streak, slightly greener yellow than
pyrite
G. Bornite (63% Cu)
 purple-blue iridescent tarnish, BRONZY on FRESH
SURFACE
H. Covellite (66% Cu)
 ELECTRIC BLUE, platy cleavage
I. Chalcocite (79% Cu)
 black, SECTILE
J. Galena
 3 perfect CLEAVAGES at right angles, DENSITY, lead-gray
color
 secondary lead minerals: anglesite, cerussite, pyromorphite
J. Molybdenite
 chief ore of molybdenum
 SOFT, slightly bluer-gray than graphite (compare it with a
pencil ‘lead’)
L. Pyrite
 often in good crystals (pyritohedra, cubes, octahedra); brittle,
black streak
M. Arsenopyrite
 no cleavage, "garlic" smell sometimes when broken
N. Pyrrhotite
 bronzy color, sometimes magnetic
O. Stibnite
 main ore of antimony.
 elongate crystals that are often ‘bent’; ONE PERFECT
CLEAVAGE and lower density distinguish it from galena.
 will easily melt in a candle flame
P. Graphite
 SOFT, black (like pencil "lead")
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5. [PRACTICAL PROSPECTOR'S GUIDE TO MINERALS] October 3, 2012
III- Ores (NON-Metallic)
A. Sphalerite
 resinous to sub-metallic luster
 yellow to green to red to black
 Important ore of cadmium as well
 alters to smithsonite, hydrozincite (fluorescent)
B. Wolframite
 HEAVY, reddish to black, tabular crystals with one perfect
cleavage
C. Scheelite
 White to brown, fluoresces bluish white
D. Manganese Oxides
 psilomelane is a mixture of compact manganese oxides;
mixture of earthy manganese oxides is known as wad.
 black, soft (often show dendritic stains)
E. Iron Oxides
 mixture of iron oxides is generally known as limonite
1. Hematite: red-brown streak
2. Goethite: brown streak
F. Magnetite
 black, dense, MAGNETIC
G. Cassiterite
 black; glassy to resinous luster
H. Cinnabar
 red; bright red streak; soft
I. Cuprite
 red, often associated with malachite or other secondary copper
minerals
J. Malachite/Azurite
 both are alteration products of other copper minerals
 (MALACHITE is GREEN; AZURITE is BLUE (‘azure-blue’,
in fact)
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6. [PRACTICAL PROSPECTOR'S GUIDE TO MINERALS] October 3, 2012
IV- Industrial Minerals
Diamond
 as adamantine crystals in kimberlite or lamprophyre
 placer deposits (weathered kimberlites/lamprophyres)
Sulfur
 as a native element in sedimentary rocks (often associated with
petroleum)
Barite
 one to two good cleavages, VERY heavy
 in hydrothermal veins and sedimentary exhalative deposits
Gypsum
 white to gray, softness is characteristic
 sedimentary rocks
Magnesite
 generally white
 found most commonly in sedimentary rocks, but also in
carbonatites
 hydromagnesite and epsomite are evaporites found in playa
lakes (from the alteration of volcanic rocks)
Apatite
 hexagonal crystals, many colors
 found in many environments
 distinguished from beryl by its hardness (beryl cannot be
scratched by a knife)
Zeolite Group
 generally white or off-white
 found in volcanic rocks or low grade metamorphic rocks
 economic deposits found as beds of altered volcanic ash
 "boil" when torched
Fluorite
 four directions of perfect CLEAVAGE
Corundum
 HARDNESS of 9
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7. [PRACTICAL PROSPECTOR'S GUIDE TO MINERALS] October 3, 2012
V- Gem Minerals
The following are reasonable to be expected, or have already been found in British
Columbia.
Corundum
 Ruby: red corundum coloured by chromium
 Sapphire: BLUE, green, pink, yellow, colourless corundum coloured
by iron and/or titanium
Diamond
Beryl
 hexagonal cross-section; prismatic to tabular crystals; generally in
pegmatites
Varieties of Beryl:
 Aquamarine: blue to green beryl coloured by iron
 Emerald: green beryl coloured by chromium or vanadium
 Goschenite: colourless beryl (originally cesium-bearing beryl)
 Heliodor: yellow beryl coloured by iron
Tourmaline
 diamond-shape cross-section; perfect basal cleavage (perpendicular to
the length of the crystal)
Varieties of Gemmy Tourmaline:
 Schorl: black tourmaline found in simple pegmatites, hydrothermal
veins and metamorphic rocks
 Elbaite: lithium-bearing tourmaline found almost exclusively in
pegmatites;
 Rubellite (pink), Verdelite (green), Indicolite (blue), Achroite
(colourless)
 Liddicoatite: another lithium-bearing tourmaline, again in pegmatites
Topaz
 diamond-shape cross-section; perfect basal cleavage (perpendicular to
the length of the crystal)
Garnet
 metamorphic rocks; pegmatites
Varieties of Gemmy Garnet:
 Grossular: gem brown variety is hessonite
 Andradite: gem green variety is demantoid
 Spessartine: bright orange is best quality
Quartz
Varieties of Quartz:
 Amethyst: purple quartz coloured by iron (Fe4+)
 Citrine: yellow/orange quartz coloured by iron
 Smoky Quartz: brown to black quartz affected by radiation
 Rose Quartz: pink quartz coloured by manganese
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8. [PRACTICAL PROSPECTOR'S GUIDE TO MINERALS] October 3, 2012
 Chalcedony: cryptocrystalline quartz; gray, greasy to silky luster;
found in volcanic rocks and some sedimentary rocks
 Agate: concentrically banded chalcedony; variously coloured
 Onyx: flat, layered chalcedony; usually black/white or red/white<
 Carnelian: chalcedony coloured red by iron
 Chrysoprase: chalcedony coloured green by nickel
 Jasper: chalcedony coloured red, green, yellow or black by iron oxide
Opal
 in volcanic and sedimentary rocks
 common versus precious opal
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