pyrophyllite
Sign in to savePyrophyllite is a phyllosilicate mineral composed of aluminium silicate hydroxide: Al2Si4O10(OH)2. It occurs in two forms (habits): crystalline folia and compact masses; distinct crystals are not known.
Key facts
- Mineral.name
- Pyrophyllite
- Mineral.category
- Phyllosilicate minerals
- Mineral.group
- Pyrophyllite-Talc group
- Mineral.boxbgcolor
- dfce9d
- Mineral.image
- Pyrophyllite-118706.jpg
- Mineral.imagesize
- 260px
- Mineral.caption
- Pearly radial cluster of pyrophyllite from Hillsborough District, Orange County, North Carolina (Size: 11 × 7.3 × 6.6 cm)
- Mineral.formula
- Al2Si4O10(OH)2
- Mineral.IMAsymbol
- Prl
- Mineral.molweight
- 360.31 g/mol
- Mineral.system
- Monoclinic or triclinic
- Mineral.class
- Prismatic (2/m) or pinacoidal ()
- Mineral.symmetry
- C2/c or C
- Mineral.unit cell
- a = 5.16 Å, b = 8.966(3) Å, c = 9.347(6) Å; α = 91.18°, β = 100.46°, γ = 89.64°; Z = 2
- Mineral.color
- Brown green, brownish yellow, greenish, gray green, gray white
- Mineral.habit
- Compact spherulitic aggregates of needlelike radiating crystals; as fine grained foliated laminae, granular, massive
- Mineral.cleavage
- [001] Perfect
- Mineral.tenacity
- Flexible inelastic
via Wikipedia infobox
~3 min read
Encyclopedic overview
5 sectionsContents
- Occurrence
- Uses
- See also
- References
- External links
Pyrophyllite is a phyllosilicate mineral composed of aluminium silicate hydroxide: Al2Si4O10(OH)2. It occurs in two forms (habits): 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. 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.
Excerpted from Wikipedia’s “pyrophyllite” article, available under the CC BY-SA 4.0 licence.