Name/Title
Muscovite / LazuliteEntry/Object ID
2009.62.144Description
Description: Common Name: Muscovite / Lazulite
Chemistry: KAl2(AlSi3O10)(F, OH)2, Potassium aluminum silicate hydroxide fluoride. / (Mg, Fe)Al2(PO4)2(OH)2, Magnesium Iron Aluminum Phosphate Hydroxide.
Class: Silicates / Phosphates
Location: Kane Creek, Jackson County, OR
Description: Highly crystalline structure of mica with a slightly green hue and a small scattering of bluish crystal imbedded in the main body.
PHYSICAL CHARACTERISTICS OF MUSCOVITE:
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.
PHYSICAL CHARACTERISTICS OF LAZULITE:
Color is dark azure-blue to a bright indigo blue or even a pale sky blue.
Luster is vitreous to dull.
Transparency: Specimens are translucent to less commonly transparent.
Crystal System: Monoclinic; 2/m
Crystal Habits include a dipyramidal form that comes close to looking like a distorted octahedron, usually flattened to the point of being a tabular crystal. Also granular and massive.
Cleavage is distinct in one direction.
Fracture is uneven.
Hardness is 5.5 - 6.
Specific Gravity is approximately 3.1 (average for translucent minerals)
Streak is pale blue to white.
Other characteristics: Clear gemmy crystals show strong pleochroism (yellowish, clear, blue) and crystals are only slightly soluble in warm hydrochloric acid..
Associated Minerals are quartz, rutile, kyanite, andalusite, garnets, muscovite, corundum, wardite, brazilianite and siderite.
Best Field Indicators: color, poor reaction to acids, crystal habit, associations and localities.
Occurrence: Notable Occurrences include India, Pakistan, Brazil and many USA locallities.
Variety: Muscovite is a common rock forming mineral and is found in igneous, metamorphic and detrital sedimentary rocks.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationLocation
Location
Display Case
FS-6Room
Frieda Smith HallBuilding
Crater Rock MuseumDate
January 3, 2024Location
Container
CenterDrawer
2nd ShelfShelf
Right, RightWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Steve MillerDate
February 9, 2010Location
Drawer
3rd from leftShelf
Right side Bottom sh, Right side Bottom shWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Scott LonganDate
September 26, 2009Location
Container
LeftDrawer
BottomShelf
LeftCabinet
Case# 30Wall
EastBuilding
Freida Smith HallCategory
Permanent
