Pyrophyllite is a
phyllosilicate mineral composed of
aluminium silicate hydroxide: Al
2Si
4O
10(OH)
2. It occurs in two forms (
habit
A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously. s): crystalline folia and compact masses; distinct
crystals are not known.
The folia have a pronounced pearly
luster, owing to the presence of a perfect cleavage parallel to their surfaces: they are flexible but not elastic, and are usually arranged radially in fan-like or spherical groups. This variety, when heated , exfoliates and swells up to many times its original volume, hence the name pyrophyllite, from the Greek ''pyro-'' (πυρο-, the combining form of πῦρ fire) and ''phyllos'' (a leaf),
[ given by R. Hermann in 1829. The color of both varieties is white, pale green, greyish or yellowish; they are very soft ( hardness of 1.0 to 1.5) and are greasy to the touch. The specific gravity is 2.65 - 2.85. The two varieties are thus very similar to talc.
]
Occurrence
Pyrophyllite occurs in phyllite and schistose rocks, often associated with kyanite, of which it is an alteration product. It also occurs as hydrothermal deposits. Typical associated minerals include: kyanite, andalusite, topaz, mica and quartz.[
Deposits containing well-crystallized material are found in:][
* Manuels, Newfoundland and Labrador, Canada, talc-like bright white appearance, high grade, no impurities; 21 million ton deposit. Currently 2 square miles owned and operated b]
Trinity Resources Ltd
and the surrounding 20 km2 including the Dog Pond and Trout Pond owned by White Fox Silver Resources Inc.
*Russia - pale green foliated masses, very like talc in appearance, are found at Beresovsk
Beryozovskoye deposit, Berezovskoe gold deposit, Berezovsky deposit, Berezovsk Mines, and some other names (russian: Берёзовское месторождение) is the first known primary deposit of gold in Russia. It is located 13 km north ...
near Yekaterinburg in the Urals.
* St. Niklas, Zermatt, Valais, Switzerland
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* Vaastana, Kristianstad, Sweden
Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
* Near Ottrje, Ardennes Mountains, Belgium
Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to ...
* Ibitiara, Bahia, Brazil
* Nagano Prefecture, Japan
* Near Ogilby, Imperial County at Tres Cerritos, Mariposa County, and the Champion mine, White Mountains, Mono County, California, USA
* Near Quartzsite, La Paz County, Arizona, USA
* Large deposits at the Deep River region of North Carolina, USA
*Graves Mountain, Lincoln County, Georgia, USA
In South Africa, major deposits of pyrophyllite occur within the Ottosdal region, where it is mined for the production of a variety of manufactured goods, and blocks are quarried and marketed as "Wonderstone" for the carving of sculptures.[Nel, LT., H. Jacobs, J.T. Allen and G.R. Bozzoli 1937. ''Wonderstone''. Geological Survey of South Africa Bulletin no. 8.]
Uses
The compact variety of pyrophyllite is used for slate pencils and tailors' chalk ( French chalk), and is carved by the Chinese into small images and ornaments of various kinds. Other soft compact minerals ( steatite and