Muscovite

Object/Artifact

-

Crater Rock Museum

Muscovite

Muscovite

Name/Title

Muscovite

Entry/Object ID

2009.62.151

Description

Chemical Composition: KAI2(AISi3O10)(F,OH)2 Crystal System: Monoclinic System Description: Common Name: Muscovite Chemistry: KAl2(AlSi3O10)(F, OH)2, Potassium aluminum silicate hydroxide fluoride. Class: Silicates Location: Maine Description: Large, thin layered, translucent sheets, smoky brown in color. PHYSICAL CHARACTERISTICS: Color is white, silver, yellow, green and brown. Luster is vitreous to pearly. Transparency crystals are transparent to translucent. Crystal System is monoclinic; 2/m Crystal Habits include tabular crystals with a prominant pinacoid termination. Muscovites four prism faces form diamond shaped "books" and if modified by another pinacoid they form pseudo-hexagonal crystal "books". The sides of the crystal often tend to tapper. Also as lamellar rock forming masses and small flakes in detrital matterial. Twinned crystals can form flat five pointed stars. Cleavage is perfect in one direction producing thin sheets or flakes. Fracture is not readily observed due to cleavage but is uneven. Hardness is 2 - 2.5. Specific Gravity is approximately 2.8 (average) Streak is white. Associated Minerals are quartz, feldspars, beryl and tourmalines. Other Characteristics: cleavage sheets are flexible and elastic, meaning they can be bent and will flex back to original shape. Best Field Indicators are crystal habit, cleavage, elastic sheets, color and associations. Fracture: Uneven Hardness: 3 Calcite Luster: Pearly Occurrence: Notable Occurrences include India, Pakistan, Brazil and many USA locallities. Rock Type: Metamorphic Specific Gravity: 2.8 Streak: White Variety: Muscovite is a common rock forming mineral and is found in igneous, metamorphic and detrital sedimentary rocks.

Collection

RAGM Mineral Collection

Acquisition

Accession

2009.62

Source or Donor

Museum Collection of Minerals

Acquisition Method

Donation

Dimensions

Width

5 in

Depth

1/2 in

Length

8 in

Weight

1.78 oz

Location

Location

Shelf

CS-E-3

Room

Curation Storage

Building

Crater Rock Museum

Category

Storage

Date

July 29, 2023