Name/Title
Labradorite var. SunstoneEntry/Object ID
2009.62.149Description
Description: Common Name: Labradorite var. Sunstone
Chemistry: Ca(50-70%) Na(50-30%) (Al, Si)AlSi2 O8, Calcium sodium aluminum silicate.
Group: Feldspars
Location: Harney County, OR
Description: Four specimens with three of them very similar in appearance. Orange to copper colored with a refractive sheen when seen at a certain angle of light. One specimen is a larger size with a transparent smoky tan color.
PHYSICAL CHARACTERISTICS:
Color is gray to smoky black.
Luster is dull to vitreous.
Transparency crystals are transparent to translucent.
Crystal System is triclinic; bar 1
Crystal Habits include blocky crystals that rarely form free of the host rock and therefore do not usually show their full crystal forms. In sliced sections of rock, the labradorite appears as blocky chunks with a predominance of near right angled corners. Twinning is common and pervasive so that in labradorite it produces a layered or stacked effect. The twin layers are typically only fractions of millimeters to several millimeters thick. Crystals of labradorite are found imbedded in gabbros and other mafic igneous rocks of low silica content. In anorthosites, labradorite is a main constituent.
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 2.70 - 2.74 (average)
Streak is white.
Associated Minerals are biotite, pyroxene and hornblende.
Other Characteristics: index of refraction is 1.55 - 1.75. Play of colors called labradorescence seen from certain directions can cause flashes of blue, violet and green and sometimes orange and yellow.
Best Field Indicators are occurrence, twinning striations and labradorescence.
Occurrence: Notable Occurrences include Sri Lanka; New York, USA; Russia; Sweden and Canada.
Variety: Oligoclase is not a well known mineral but has been used as a semi-precious stone under the names of sunstone and moonstone. Sunstone has flashes of reddish color caused by inclusions of hematite. Moonstone shows a glowing shimmer similar to labradorescence, but lacking in color.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationOther Names and Numbers
Other Number
Other Number: A,B,C,DLocation
Location
Shelf
CS-I-1Room
Curation StorageBuilding
Crater Rock MuseumDate
February 3, 2024Notes
Only (D) is present in this locationLocation
Drawer
3rd from RightShelf
Right bottom front, Right bottom frontWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Scott LonganDate
September 26, 2009