Pyrophyllite Value, Price, and Jewelry Information

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Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

Pyrophyllite resembles talc in many ways and is indistinguishable by eye from soapstone. Chemical tests are needed to distinguish them. North Carolina material is often used in carvings, as is the material from China known as agalmatolite.

Pyrophyllite Information

Data	Value
Name	Pyrophyllite
Stone Sizes	Cabochons and carvings are cut from massive material, any practical size.
Formula	Al₂Si₄O₁₀(OH)₂.
Colors	White, yellow, pale blue, grayish green, brownish green.
Hardness	1-2
Cleavage	Perfect 1 direction
Crystallography	Monoclinic. Crystals tabular, often curved and deformed; foliated, radial, granular, compact.
Refractive Index	1.534-1.601
Birefringence	0.050
Luminescence	Weak cream white in LW (China) — variety called agalmatolite.
Luminescence Present	Yes
Luminescence Type	Fluorescent, UV-Long
Absorption Spectrum	Not diagnostic.
Optics	a = 1.534-1.556; β = 1.586-1.589; γ = 1.596-1.601. Biaxial (-), 2V = 53-62°. Vague shadow edge on refractometer at about 1.6.
Optic Sign	Biaxial -
Luster	Pearly to dull, greasy.
Specific Gravity	2.65-2.90
Transparency	Translucent to opaque.

Optics: a = 1.534—1.556; β= 1.586-1.589; γ= 1.596-1.601.

Biaxial (-), 2V = 53—62°.

Vague shadow edge on refractometer at about 1.6.

Occurrence: In schistose metamorphic rocks; also in hydrothermal veins with micas, quartz.

California; Arizona; Deep River, North Carolina; Pennsylvania; Georgia.

Minus Gerais, Brazil; Mexico; Sweden; Belgium;

Switzerland; Japan; USSR; Korea.

Transvaal, South Africa: so-called koranna stone, which is dark gray and is about 86% pyrophyllite; R.I. ~ 1.58, S.G. 2.72; also called South African Wonderstone.

Comments: Pyrophyllite resembles talc in many ways and is indistinguishable by eye from soapstone. Chemical tests are needed to distinguish them. North Carolina material is often used in carvings, as is the material from China known as agalmatolite.

Name: From the Greek words for fire and leaf because of the sheet-like nature and thermal properties of the mineral. Agalmatolile means figure stone, in allusion to its use in carvings.