Difference between revisions of "Talc"

Latest revision as of 14:02, 28 December 2022

Soapstone sculpture
MFA# 2001.218

Description

A soft, slippery mineral composed of hydrated magnesium silicate. Talc is found in veins and masses in metamorphic rocks; large deposits occur in Austria (Tyrol), Italy (Florence), Switzerland, Germany (Bavaria), England (Cornwall), Scotland (Shetland), Canada (Quebec, Ontario), and the U.S. (New England, New York, Pennsylvania, Maryland, North Carolina, Texas). Talc, mixed with other minor minerals, occurs in the stone called Steatite, or soapstone. It is usually a white, green or gray color. Talc is so soft, it can be scratched with a fingernail. It has a waxy luster and a greasy feel. Steatite was used in antiquity for small carved objects, such as cylinder seals, scarabs, amulets, bowls, boxes, beads, and statuary. After carving, some pieces were baked to dehydrate the talc and thus harden the stone. Currently, talc is often crushed and used as a filler in paper, ceramics, paint, plastics, rubber, soaps, plaster, crayons, and cosmetics. It has also been used as a lubricant, leather dressing, dusting powder, and as an insulating material. Talc is used on the inside of powdered gloves and can leave residual powder on contacted surfaces. Since soapstones are resistant to most chemical reagents, and to moderate heat, they have been used for sinks and countertops.

Talc

Synonyms and Related Terms

hydrated magnesium silicate; Pigment White 26; talc (Fr.); talk (Ned., Sven., Pol.); talco (Esp., It., Port.); Talk (Deut.); Talkum (Deut.); talkis (Gr.); talcum; soapstone; steatite; asbestine; French chalk; tailors chalk; Mistron®; Vertal; Nicron®;

Talc micrograph

FTIR (MFA)

Raman(U of Parma)

Chemical structure

Risks

Noncombustible.
Some samples may contain asbestos.
Talc USA: MSDS

Physical and Chemical Properties

Insoluble in water, cold acids or alkalis
Ground particles can be very small (2.0 micrometers).
Talc occurs naturally in foliated to fibrous masses
Perfect cleavage in one direction producing thin laminar particles
Fracture = uneven
Luster = pearly, greasy
Streak = white to pearl black
Fluorescence = inert to weak pink or yellowish in LW; inert to pale orange in SW

Composition	Mg3Si4O10(OH)2
CAS	14807-96-6
Mohs Hardness	1.0
Density	2.5-2.8 g/ml
Refractive Index	1.539; 1.589; 1.589
Birefringence	0.050 - 0.051

Comparisons

Properties of Common Abrasives

Characteristics of Common White Pigments

Resources and Citations

Mineralogy Database: Talc
Gem Identification Lab Manual, Gemological Institute of America, 2016.
Nicholas Eastaugh, Valentine Walsh, Tracey Chaplin, Ruth Siddall, Pigment Compendium, Elsevier Butterworth-Heinemann, Oxford, 2004
R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966
G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 793
Encyclopedia Britannica, http://www.britannica.com Comment: "talc" [Accessed March 4, 2002].
C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
Wikipedia: Talc (Accessed Sept. 17, 2005 and Dec 2022)
The Dictionary of Paper, American Paper Institute, New York, Fourth Edition, 1980
The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 9207
Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000

CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: density=2.7-2.8

@@ Line 1: / Line 1: @@
-[[File:2000.1293-SC116389.jpg|thumb|]]
+[[File:2000.1293-SC116389.jpg|thumb|Soapstone sculpture<br>MFA# 2001.218]]
 == Description ==
-A soft, slippery mineral composed of hydrated magnesium silicate. Talc is found in veins and masses in metamorphic rocks; large deposits occur in Austria (Tyrol), Italy (Florence), Switzerland, Germany (Bavaria), England (Cornwall), Scotland (Shetland), Canada (Quebec, Ontario), and the U.S. (New England, New York, Pennsylvania, Maryland, North Carolina, Texas). Talc, mixed with other minor minerals, occurs in the stone called [http://cameo.mfa.org/materials/fullrecord.asp?name=steatite steatite], or soapstone. It is usually a white, green or gray color. Talc is so soft, it can be scratched with a fingernail. It has a waxy luster and a greasy feel. Steatite was used in antiquity for small carved objects, such as cylinder seals, scarabs, amulets, bowls, boxes, beads, and statuary. After carving, some pieces were baked to dehydrate the talc and thus harden the stone. Currently, talc is often crushed and used as a filler in paper, ceramics, paint, plastics, rubber, soaps, plaster, crayons, and cosmetics. It has also been used as a lubricant, leather dressing, dusting powder, and as an insulating material. Talc is used on the inside of powdered gloves and can leave residual powder on contacted surfaces. Since soapstones are resistant to most chemical reagents, and to moderate heat, they have been used for sinks and countertops.
+A soft, slippery mineral composed of hydrated magnesium silicate. Talc is found in veins and masses in metamorphic rocks; large deposits occur in Austria (Tyrol), Italy (Florence), Switzerland, Germany (Bavaria), England (Cornwall), Scotland (Shetland), Canada (Quebec, Ontario), and the U.S. (New England, New York, Pennsylvania, Maryland, North Carolina, Texas). Talc, mixed with other minor minerals, occurs in the stone called [[steatite]], or soapstone. It is usually a white, green or gray color. Talc is so soft, it can be scratched with a fingernail. It has a waxy luster and a greasy feel. Steatite was used in antiquity for small carved objects, such as cylinder seals, scarabs, amulets, bowls, boxes, beads, and statuary. After carving, some pieces were baked to dehydrate the talc and thus harden the stone. Currently, talc is often crushed and used as a filler in paper, ceramics, paint, plastics, rubber, soaps, plaster, crayons, and cosmetics. It has also been used as a lubricant, leather dressing, dusting powder, and as an insulating material. Talc is used on the inside of powdered gloves and can leave residual powder on contacted surfaces. Since soapstones are resistant to most chemical reagents, and to moderate heat, they have been used for sinks and countertops.
 [[File:Talcemr3.jpg|thumb|Talc]]
 == Synonyms and Related Terms ==
 hydrated magnesium silicate; Pigment White 26; talc (Fr.); talk (Ned., Sven., Pol.); talco (Esp., It., Port.); Talk (Deut.); Talkum (Deut.); talkis (Gr.); talcum; soapstone; steatite; asbestine; French chalk; tailors chalk; Mistron®; Vertal; Nicron®;
+[[File:soapstonelarge.jpg|thumb|Talc micrograph]]
+[[[SliderGallery rightalign|Talc,Harvard Mineral Museum,53201.TIF~FTIR (MFA)|Talcitaly1.jpg~Raman(U of Parma)|talc.jpg~Chemical structure]]]
+== Risks ==
-[[[SliderGallery rightalign|Talcitaly1.jpg~Raman|MFA- Talc.jpg~FTIR|talc.jpg~Chemical structure]]]
+* Noncombustible.
+* Some samples may contain asbestos.
-== Other Properties ==
+* Talc USA: [http://www.talcusa.com/wp-content/uploads/2015/11/TALC-USA-8020-MSDS-01202015.pdf MSDS]
-Ground particles can be very small (2.0 micrometers).
-Talc occurs naturally in foliated masses.  Perfect cleavage in one direction producing thin laminar particles.  Streak = white.  Fracture = uneven.  Luster = pearly, greasy.
-Strongly birefringent under crossed polars
-Insoluble in water, cold acids or alkalis
+== Physical and Chemical Properties ==
+* Insoluble in water, cold acids or alkalis
+* Ground particles can be very small (2.0 micrometers).
+* Talc occurs naturally in foliated to fibrous masses
+* Perfect cleavage in one direction producing thin laminar particles
+* Fracture = uneven
+* Luster = pearly, greasy
+* Streak = white to pearl black
+* Fluorescence = inert to weak pink or yellowish in LW; inert to pale orange in SW
 {| class="wikitable"
@@ Line 33: / Line 37: @@
 |-
 ! scope="row"| Density
-| 2.5-2.8
+| 2.5-2.8 g/ml
-|-
-! scope="row"| Molecular Weight
-| mol. wt. = 379.3
 |-
 ! scope="row"| Refractive Index
 | 1.539; 1.589; 1.589
+|-
+! scope="row"| Birefringence
+| 0.050 - 0.051
 |}
-== Hazards and Safety ==
-Noncombustible. Some samples may contain asbestos.
-LINK: [http://www.cdc.gov/niosh/ipcsneng/neng0329.html International Chemical Safety Card]
-== Additional Information ==
-Mineralogy Database: [http://www.webmineral.com/data/Talc.shtml Talc]
 == Comparisons ==
-[[media:download_file_228.pdf|Properties of Common Abrasives]]
+[[media:download_file_209.pdf|Properties of Common Abrasives]]
-[[media:download_file_524.pdf|Characteristics of Common White Pigments]]
-== Additional Images ==
+[[media:download_file_517.pdf|Characteristics of Common White Pigments]]
-<gallery>
+== Resources and Citations ==
-File:soapstonelarge.jpg|Talc micrograph
-</gallery>
-== Authority ==
+* Mineralogy Database: [http://www.webmineral.com/data/Talc.shtml Talc]
+* Gem Identification Lab Manual, Gemological Institute of America, 2016.
 * Nicholas Eastaugh, Valentine Walsh, Tracey Chaplin, Ruth Siddall, ''Pigment Compendium'', Elsevier Butterworth-Heinemann, Oxford, 2004
 * R. J. Gettens, G.L. Stout, ''Painting Materials, A Short Encyclopaedia'', Dover Publications, New York, 1966
 * G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971  Comment: p. 793
+* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "talc" [Accessed March 4, 2002].
-* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "talc" Encyclopædia Britannica [Accessed March 4, 2002].
 * C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979
+* Wikipedia: [https://en.wikipedia.org/wiki/Talc Talc] (Accessed Sept. 17, 2005 and Dec 2022)
-* Wikipedia, the free encyclopedia, at http://www.wikipedia.com  Comment: http://en.wikipedia.org/wiki/Talc (Accessed Sept. 17, 2005)
 * ''The Dictionary of Paper'', American Paper Institute, New York, Fourth Edition, 1980
 * ''The American Heritage Dictionary'' or ''Encarta'', via Microsoft Bookshelf 98, Microsoft Corp., 1998
 * Richard S. Lewis, ''Hawley's Condensed Chemical Dictionary'', Van Nostrand Reinhold, New York, 10th ed., 1993
 * Michael McCann, ''Artist Beware'', Watson-Guptill Publications, New York City, 1979
 * Matt Roberts, Don Etherington, ''Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology'', U.S. Government Printing Office, Washington DC, 1982
 * ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
 * Random House, ''Webster's Encyclopedic Unabridged Dictionary of the English Language'', Grammercy Book, New York, 1997
 * ''The Merck Index'', Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983  Comment: entry 9207
+* Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
-* Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
 * ''CRC Handbook of Chemistry and Physics'', Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980  Comment: density=2.7-2.8