Name/Title
AlbiteEntry/Object ID
2009.62.137Description
Chemical Composition: Sodium aluminum silicate
Crystal System: Triclinic System
Description: Common Name: Albite
Chemistry: NaAlSi3 O8, Sodium aluminum silicate.
Group: Feldspars
Location: Minas Gerais, Brazil
Description: Large angular crystals with relatively smooth faces with no particular plane of symmetry. The color is a creamy gray and white with a granular tan matrix.
PHYSICAL CHARACTERISTICS:
Color is usually white (Albite is derived from the same root word as albino) or colorless but can be shades of blue, yellow, orange and brown.
Luster is vitreous to dull if weathered..
Transparency crystals are translucent to opaque and only sometimes transparent.
Crystal System is triclinic; bar 1
Crystal Habits include blocky, tabular and platy crystals. The typical crystal has a nearly rectangular or square cross-section with slightly slanted dome and pinacoid terminations. A variety called Cleavelandite forms very thin platy crystals that can grow rather large (15+ cm across) but can maintain an even thickness of only a few millimeters. Twinning is almost universal in albite. Crystals can be twinned according to the Albite, Carlsbad, Manebach and Baveno laws. Albite is a common constituent of granitic and syenite rocks. Can also be massive.
Cleavage is perfect in one and good in another direction forming nearly right angled prisms.
Fracture is conchoidal.
Hardness is 6 - 6.5.
Specific Gravity is approximately 2.61 (average)
Streak is white.
Associated Minerals are quartz, tourmaline and muscovite.
Other Characteristics: index of refraction is 1.53. Lamellar twinning may cause a grooved effect on cystal surfaces that appear as striations. Some albite may show an opalescence due to twinning and is referred to as moonstone.
Best Field Indicators are occurence, crystal habit, twinning, striations, density and index of refraction.
Fracture: uneven
Hardness: 6 Orthoclase
Luster: Vitreous
Occurrence: Albite is the last of the feldspars to crystallize from molten rock. The process of crystallization from a molten rock body serves to isolate rarer elements in the last stages of crystallization and therefore produces rare mineral species. Thus albite is often found with some lovely rare and beautiful minerals. Although usually not an exceptional collection mineral in itself, albite can be a nice accessory mineral to other mineral species. A variety associated with tourmaline is called cleavelandite and forms extremely thin, platy, white and sometimes very transparent crystals.
Rock Type: Igneous
Specific Gravity: 2.61
Streak: white
Variety: Albite is a common felspar and is the "pivot" mineral of two different feldspar series. It is most often associated with the plagioclase series where it is an end member of this series. The plagioclase series comprises felspars that range in chemical composition from pure NaAlSi3 O8 to pure CaAl2 Si2 O8 . The various plagioclase feldspars are identified from each other by gradations in index of refraction and density in the absence of chemical analysis and/or optical measurements. Albite is also an end member of the alkali or K-feldspars whose series ranges from pure NaAlSi3 O8 to pure KAlSi3 O8. This series only exists at high temperatures with the mineral sanidine being the potassium, K, rich end member. At lower temperatures, the K-feldspars will seperate from the albite in a process called exsolution. The albite will form layers inside the k-feldspars crystals. Some times these layers are discernable to the naked eye and the stone is referred to as perthite. Albite by definition must contain no less than 90% sodium and no more than 10% of either potassium and/or calcium in the cation position in the crystal structure..Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
4-3/8 inDepth
3-5/8 inLength
4-1/8 inWeight
2.13 ozLocation
Location
Display Case
FS-6Room
Frieda Smith HallBuilding
Crater Rock MuseumDate
January 3, 2024Location
Container
CenterDrawer
3rd ShelfShelf
Right, RightWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Steve MillerDate
January 30, 2010Location
Drawer
5th from rightShelf
3rd shelf right side, 3rd shelf right sideWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Scott LonganDate
September 26, 2009Location
Container
Center / FrontDrawer
BottomShelf
RightCabinet
Case# 30Wall
EastBuilding
Freida Smith HallCategory
Permanent