Talc its types and occurrence

1. PRESENTATION
BY; UBAIDULLAH SHALMANI
M AWAIS AZIZ
SESSION; (2014-2018)
SUBJECT; MINERALOGY
SEMESTER; 5TH
DEPARTMENT OF GEOLOGY
UNIVERSITY OF MALAKAND

2. TALC

3. What is Talc?
Talc is a Sheet Silicate mineral.
 It is associated with clays and also with Smectite
group.
The symmetry of Talc is Monoclinic (a ≠ b ≠ c , α = γ
= 90° and β ≠ 90°)
It is biaxial negative.

4.  The formula of Talc is Mg3Si4O10(OH)2, Magnesium
Silicate Hydroxide.
TYPES OF TALC:
1) PLATY TALC: It contains predominately (>90%)
the mineral talc.
Platy talc's can be further classified as microcrystalline
or macro crystalline.

5. a) MICRO CRYSTALLINE: These varieties are
naturally small in plate size and comprise
compact, dense ores.
b) MACRO CRYSTALLINE: These varieties
contain relatively large, higher aspect ratio plates.

6. 2) TREMOLITIC TALC: It is most often a natural
blend of talc, tremolite, serpentine and anthophyllite.
The size of an individual talc platelet (= a few
thousand elementary sheets) can vary from
approximately 1 micron to over 100 microns
depending on the deposit.

7. FORMATION
Talc is a metamorphic mineral that results from the
metamorphism of Magnesium minerals such as
serpentine, pyroxene, amphibole, and olivine, in the
presence of carbon dioxide and water.
 This is known as “talc carbonation” and produces a
suite of rocks known as talc carbonates.

8. FORMATION
Talc is primarily formed by hydration and carbonation
by this reaction:
2Mg3Si2O5(OH)4 + 3CO2 → Mg3Si4O10(OH)2 + 3MgCO3 +
3 H2O
Talc can also be formed from Magnesium chlorite and
quartz in blue schist and Eclogite metamorphism by
the following metamorphic reaction:

9. FORMATION
Chlorite + Quartz → Kyanite + Talc + Water
Talc can also be formed via a reaction between
dolomite and silica.
3CaMg(CO3)2 + 4SiO2 + H2O → Mg3Si4O10 (OH)2 +
3 CaCO3 + 3 CO2

10. OCCURRENCE
Talc is a common metamorphic mineral in metamorphic
belts that contain ultramafic rocks, such as soap stone (a
high- talc rock), and with in white schist and blue schist
metamorphic terranes.
Pakistan has major resources of best quality Talc
Deposits in the world. Its largest deposits located in
Sherwan (Hazara), Shangla (Swat), Jamrud, Kurram
Agency, Safed Koh (near Parachinar), Landi Kotal, Zhob
in Baluchistan, Nauseri in Azad Jammu & Kashmir and
Chalt in Gilgit-Baltistan.

11. OCCURRENCE
 The largest talc mine at Trimouns near Luzenac in
southern France produces 400,000 tones of talc per
year, representing 8% of world production.

12. PROPERTIES
 Color is usually white, gray, yellow and green.
 It can also be stained brown by iron oxides.
 Luster is greasy to dull, but pearly on cleavage
surfaces.
Transparency: Crystals are mostly translucent to
opaque.
Fracture is uneven or splintery.

13. PROPERTIES
Hardness is 1 - 1.5 (soft enough to be scratched by a
fingernail).
Specific Gravity is approximately 2.65 - 2.85
(average).
Streak is white.
Other Characteristics: Cleavage sheets are perfect. A
distinctive greasy feel to the touch.

14. PROPERTIES
Monoclinic biaxial negative.
Relief is low to moderate.
Associated Minerals: are numerous, but a short list
would include the micas, sericite, chlorite, graphite,
quartz, albite, barite, gypsum, andalusite, kyanite,
sillimanite, and epidote.

15. White Talc

16. Green Talc

17. Gray Talc

18. Yellow Talc

19. USES
Talc is used in many industries, including paper
making, plastic, paint and coatings, rubber, food,
electric cable, pharmaceuticals, cosmetics, and
ceramics.
 A coarse grayish- green high-talc rock is soap stone
or steatite, used for stoves, sinks, electrical
switchboards, crayons, soap, etc.

20. USES
It is often used for surfaces of laboratory table tops
and electrical switch boards.
 Talc finds use as a cosmetic (talcum powder), as a
lubricant, and as a filler in paper manufacture.
It is used to coat the insides of inner tubes and rubber
gloves during manufacture to keep the surfaces from
sticking.

21. USES
Talc, with heavy refinement, has been used in baby
powder, and a stringent powder used to prevent diaper
rash.
It is also often used in basket ball to keep a player’s
hands dry.
Most tailor’s chalk, or French chalk, is talc , as is the
chalk often used for welding or metal working.

22. USES
Due to its low shear strength, talc is one of the oldest
known solid lubricants.
Talc is widely used in the ceramics industry in both
bodies and glazes.
Talc is sometimes used as an adulterant to illegal
heroin, to expand volume and weight and thereby
increase its street value.

23. USES
Talc is used in the production of the materials that are
widely used in the building interiors such as base
content paints in wall coatings.
 Other uses of talc to a great extent are organic
agriculture, food industry, cosmetics, and hygiene
products such as baby powder and detergent powder.

24. THANKS