Pyrophyllite

Pyrophyllite-Talc Group. The Al analogue of ferripyrophyllite. Two polytypes are known, a monoclinic one (2M) and a triclinic one (1A).

Structural context

Pyrophyllite
Crystal System triclinicSpace Group P-1
a4.9815—5.1919 (5.1341)
b8.8219—9.1224 (8.9469)
c9.347—18.55 (13.3048)
alpha90—91.18 (90.6203)
beta95.83—100.477 (99.5981)
gamma88.62—90 (89.6471)
volume425.157—835.901 (599.7561)

Based on 7 measurements

Chemical context

Stoichiometric formulas

Pyrophyllite
mindat.org
  • March 13, 2023Al2Si4O10(OH)2
IMA
  • March 13, 2023Al2Si4O10(OH)2
mineralogy.rocks
  • Aug. 30, 2022Al2Si4O10(OH)2

Elements recorded on EPMA

7
Al
7
O
7
Si
6
H
2
Fe
2
Mg
1
Ca

Physical properties

ColorColor entities, recognized using a custom trained NER model
    • gray
    • pale blue
    • pale green
    • brownish green
    • pale yellow
    Color noteOriginal color note from the source
    White, gray, pale blue, pale green, pale yellow, brownish green
    Lustre
    Pearly
    Dull
    Transparency
    Translucent
    Opaque
    Tenacity
    flexible
    Hardness
    1—2
    Measured density
    2.65—2.9
    Calculated density
    2.81