THE MINERAL TALC

  • Chemistry: Mg3Si4O10(OH)2, Magnesium Silicate Hydroxide
  • Class: Silicates
  • Subclass: phyllosilicates
  • Group: Clays and also The Montmorillonite/Smectite Group.
  • Uses: an ornamental and heat, acid and electrically-resistant stone (soapstone) used as counter tops, electrical switchboards, carvings, etc, used as an ingredient in paints, rubber, roofing materials, ceramics and insecticides. Most commonly known as the primary ingredient in talcum powder.
  • Specimens
Talc is an important industrial mineral. Its resistance to heat, electricity and acids make it an ideal surface for lab counter tops and electrical switchboards. It is also an important filler material for paints, rubber and insecticides. Even with all these uses, most people only know talc as the primary ingredient in talcum powder. Mineral specimens are not very common as it does not form very large crystals. However, it often replaces other minerals on an atom by atom basis and forms what are called pseudomorphs (false shape). The talc takes the form of the mineral it replaces. A specimen of what looks like milky quartz is quite a suprise when it not only has a soapy feel but can be scratched by a fingernail.

PHYSICAL CHARACTERISTICS:

  • Color is green, gray and white to almost silver.
  • Luster is dull to pearly or greasy.
  • Transparency crystals are translucent and masses are opaque.
  • Crystal System is monoclinic; 2/m.
  • Crystal Habits: never in large individual crystals, but if found are flattened tabular crystals with a hexagonal cross-section, usually talc is found in compact or lamellar masses. Forms pseudomorphs (false shape) of other crystals such as quartz, pyroxenes, olivine and amphiboles.
  • Cleavage is perfect in one direction, basal.
  • Fracture is uneven to lamellar.
  • Hardness is 1 (can leave mark on paper)
  • Specific Gravity is 2.7 - 2.8 (average)
  • Streak is white.
  • Other Characteristics: cleavage flakes are slightly flexible but not elastic and talc has a soapy feel to the touch.
  • Associated Minerals include serpentine, dolomite, magnesite, quartz, pyroxenes, olivine, biotite and amphiboles.
  • Notable Occurances: include many mines up and down the Appalachian Mountains and in California and Texas, USA; Germany; Florence, Italy; Tyrol, Austria; Transvaal, South Africa and Shetland, Scotland.
  • Best Field Indicators softness, color, soapy feel, luster and cleavage.
TALC specimens:
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TALC specimen tlc-1
$ 25.00
Dims: 2.8 x 2.4 x 1.6" (7.1 x 6.1 x 4.1 cm)
Wt: 5.69 oz. (161.5 g)
Ropes Mine, Marquette County, Michigan, U.S.A.
This hand specimen contains the most crystalline Talc that I have ever seen. Crystals have not necessarily formed completely, so it is impossible to asses size or condition. However, the Talc has a platy, micaceous habit, and almost reminds me of a soft mica schist. It has a pale green coloration and a definitely pearly, almost micaceous luster, and shows definite translucence along the specimen's edges. The Talc is in the form of veins that run through a white feldspar base rock that is partly stained a brown color. Some of it shows intense weathering, but most has crystalline tendencies (though no discernable natural form) and also possesses a pearly luster.
no photo
tlc-1 ($ 25.00)
Ropes Mine, Marquette County, Michigan, U.S.A.
TALC specimen tlc-2
$ 25.00
Dims: 4.2 x 2.7 x 1.2" (10.7 x 6.9 x 3.0 cm)
Wt: 5.95 oz. (168.5 g)
Ropes Mine, Marquette County, Michigan, U.S.A.
This specimen consists of a crust made up of almost micaceous, malformed Talc crystals that partly cover a base of what appears to be rusty quartzite and feldspar. The talc has a green color and a pearly luster, and has a form and habit that are very much like those of mica schist. There do not appear to be any discernable crystals among the formation, but the Talc definitely occurs as warped and intergrown blades. There is some black material sandwiched between the Talc and the siliceous base that I think is merely black Talc, as it is rather soft (though seemingly not as soft as the green Talc on top of it).
no photo
tlc-2 ($ 25.00)
Ropes Mine, Marquette County, Michigan, U.S.A.
TALC specimen tlc-3
$ 25.00
Dims: 7.3 x 5.7 x 1.6" (18.5 x 14.5 x 4.1 cm)
Wt: 2 lbs., 5.0 oz. (1.048 kg)
unknown
This large specimen consists of a massive chunk of almost compact, fibrous Talc. As it has no form, there really is no damage to assess. Its color is a very subtle pale pink with noticeable gray streaks running through it, and it has a moderate waxy luster. It does seem to show definite compact and fibrous tendencies, though. There are a few tiny, dark dendritic formations scattered about the piece, but I cannot identify what has caused them.
no photo
tlc-3 ($ 25.00)
unknown
TALC specimen tlc-4
$ 25.00
Dims: 3.5 x 1.9 x 1.2" (8.9 x 4.8 x 3.0 cm)
Wt: 6.28 oz. (178.2 g)
Ropes Mine, Marquette County, Michigan, U.S.A.
This specimen consists of a mass of specular, micaceous Talc that is partly intergrown with matrix rock that appears to be made up of both calcite and possibly a type of feldspar. The talc has a semicrystalline form and shows a moderate amount of fresh damage. It occurs in thin plates or sheets that are heavily intergrown and compacted. Both its form and its pearly luster strongly resemble that of mica; however, it has a pale green coloration and is a bit cloudier than most micas, being quite translucent in thin layers.
no photo
tlc-4 ($ 25.00)
Ropes Mine, Marquette County, Michigan, U.S.A.
TALC specimen tlc-5
$ 30.00
Dims: 6.2 x 5.9 x 2.1" (15.7 x 15.0 x 5.3 cm)
Wt: 3 lbs., 4.8 oz. (1.498 kg)
unknown
This large speicmen consists of an amorphous chunk of massive pink Talc. It has the classic "soapy" feel of Talc, and can be easily scratched with a fingernail. The material has a pale pink coloration and contains a few gray streaks that run along one side. The other side is mostly clear, but there are a few small, black dendritic formations visible in the material. Its luster is waxy and it is opaque, of course. There is no host or base rock present. Such a piece might be appropriate for a sculptor or one who makes small carvings.
no photo
tlc-5 ($ 30.00)
unknown
TALC specimen tlc-6
$ 40.00
Dims: 8.8 x 5.4 x 2.0" (22.4 x 13.7 x 5.1 cm)
Wt: 4 lbs., 3.5 oz. (1.915 kg)
unknown
This cabinet specimen consists of a somewhat flat, amorphous slab of massive Talc. Though showing a few fresh scars, it has no crystal form for damage to mar. It does have some layering or tendencies towards layering and has the soft, soapy texture that is standard for this mineral. Its color is a pale, uneven pink, its luster is dull and waxy, and it is completely opaque. As with most of our specimens like this one, there is no host rock present.
no photo
tlc-6 ($ 40.00)
unknown
TALC specimen tlc-7
$ 25.00
Dims: 3.0 x 1.8 x 1.8" (7.6 x 4.6 x 4.6 cm)
Wt: 3.25 oz. (92.2 g)
Ropes Mine, Marquette County, Michigan, U.S.A.
Several veins of specular Talc extend through the host material of this specimen. The Talc that forms these veins does not show any definite crystal form, but is as close to being crystalline as I have ever seen in this species. Its occurrence strongly resembles that of a mica, and even its pale green color and bright pearly luster could be confused as such. The material is translucent to dimly transparent and has a flaky consistency. The host material seems to be made out of a rust-stained sandstone and some type of white feldspar.
no photo
tlc-7 ($ 25.00)
Ropes Mine, Marquette County, Michigan, U.S.A.
TALC specimen tlc-8
$ 25.00
Dims: 2.7 x 2.1 x 1.6" (6.9 x 5.3 x 4.1 cm)
Wt: 5.56 oz. (157.7 g)
Ropes Mine, Marquette County, Michigan, U.S.A.
A semi-crystalline Talc crust rests on the pale gray limestone base of this hand specimen. The Talc has no definite crystal form, but shows obvious crystalline tendencies. It closely resembles mica in both its platy form, green color and pearly luster. It is essentially translucent, though some sections are thin enough to show definite transparence.
no photo
tlc-8 ($ 25.00)
Ropes Mine, Marquette County, Michigan, U.S.A.
TALC specimen tal-9
$ 45.00
Dims: 3.4 x 2.4 x 2.3" (8.5 x 6.1 x 5.8 cm)
Wt: 8.7 oz. (247 g)
Texas, Lancaster County, Pennsylvania, U.S.A.
A lamellar formation of semicrystalline Talc makes up the bulk of this cabinet specimen. Though showing some damage, the formation is generally in good condition, showing flaky, almost micaceous tendencies along its sides. The Talc has a dull, gray-brown color and a micaceous, pearly luster and is opaque. A small amount of an igneous rock serves as a base.
no photo
tal-9 ($ 45.00)
Texas, Lancaster County, Pennsylvania, U.S.A.
TALC specimen tal-10
$ 35.00
Dims: 8.28x5.12x1.56" (21.04x13.00x3.95cm)
Wt: 53.86oz (1527g)
Texas, USA
This is a specimen of "Texas Pink" talc. It is quite pure, and the talc is crystalline and translucent. There are many tiny spots where the talc has altered (due to fracture, scrapes, or simple weathering) to a microcrystalline form, and these spots appear white and powdery. Of course, the talc has a greasy feel and it also has a nearly vitreous luster. The true color of this talc is a very pale pink - it is not nearly as deep a color as the images suggest (but it looked correct on the camera).
no photo
tal-10 ($ 35.00)
Texas, USA
TALC specimen tal-11
$ 25.00
Dims: 8.28x5.92x1.26" (21.04x15.03x3.21cm)
Wt: 47.16oz (1337g)
Texas, USA
ANother example of "Texas Pink" talc, this chunk of talc is not very pink. It looks almost white, but when held up to the light the pink color shows through the translucent specimen very well. Naturally, it has the greasy feel of talc, and some areas are white (or colorless but translucent) more than pink.
no photo
tal-11 ($ 25.00)
Texas, USA
TALC specimen tal-12
$ 39.00
dims mm=295x156x42
wt g=1915
China
My records indicate that this is a specimen of "Chinese Pink Talc". To my eye, there is no hint of a pink color, rather the color is more of an oyster shell. It is somewhat translucent, and has areas with a brown stain. Of course, it has a greasy feel and displays a number of white areas (indicating damage).
no photo
tal-12 ($ 39.00)
China
 

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