Pyrophyllite

Object/Artifact

-

Crater Rock Museum

Name/Title

Pyrophyllite

Entry/Object ID

78.63.463

Description

Chemical Composition: Al2Si4O10(OH)2 Crystal System: Monoclinic System Description: Common Name: Pyrophyllite Group Name: Clays Chemistry: Al2Si4O10(OH)2 Location: Yekaterinburb, Ural Mtns., Russia Description: Delmar described this specimen as one, , pyrophyillite crystals, white, with yellow to reddish stains. Crystals are kind of a star formation. Rock guide calls them radiating bundles of small crystals. Physical Characteristics: •Color is usually white, colorless, gray, yellow, pale green and/or blue. It can also be stained brown by iron oxides. •Luster is greasy to dull, but pearly on cleavage surfaces. •Transparency: Crystals are mostly translucent to opaque. •Crystal System is monoclinic; 2/m and triclinic; bar 1. •Crystal Habits include the typical fine grained, fibrous and lamellar masses, stellate aggregates and radiating spherules. Individual crystals are rare, but usually have a tabular subhedral or distorted form. •Cleavage is perfect in one direction. •Fracture is uneven or splintery. •Hardness is 1 - 1.5 (soft enough to be scratched by a fingernail). •Specific Gravity is approximately 2.65 - 2.85 (average). •Streak is white. •Other Characteristics: Cleavage sheets are flexible, but inelastic. A distinctive greasy feel to the touch. •Associated Minerals: are numerous, but a short list would include the micas, sericite, chlorite, graphite, quartz, albite, barite, gypsum, andalusite, kyanite, sillimanite, lazulite and epidote. •Notable Occurrences include Randolph, Guilford and Orange Counties, North Carolina, Chesterfield County, South Carolina; Mariposa County and San Bernardino County, California, Arizona and Graves Mountain, Georgia, USA as well as Belgium; China; Switzerland; Mexico; Minas Gerais, Brazil; Sweden; Ural Mountains, Russia; Korea and Japan. •Best Field Indicators are crystal habit, color, cleavage, softness, aluminum test and feel. Fracture: Uneven or splintery Hardness: 1 Talc Luster: Vitreous Rock Type: Metamorphic Specific Gravity: 2.65 - 2.8 Streak: white

Collection

Delmar Smith Crystal Collection

Acquisition

Accession

78.63

Source or Donor

Delmar Smith Crystal Collection

Acquisition Method

Donation

Other Names and Numbers

Other Number

Other Number: 1978.63.

Dimensions

Height

4 in

Width

3-1/4 in

Length

1-1/2 in

Dimension Notes

Dimension taken at widest points

Location

Location

Display Case

FS-9

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Permanent

Date

December 26, 2008