Name/Title
Amianthus Actinolite / AdulariaEntry/Object ID
2009.62.72Description
Chemical Composition: see description
Crystal System: Hexagonal System
Description: Common Name: Amianthus(Asbostos) Actinolite / Adularia
Chemistry: Ca2(Mg, Fe)5Si8O22(OH)2 , Calcium Magnesium Iron Silicate Hydroxide / KAlSi308
Group: Amphibole / Feldspar
Location: Etzlital Canton, Graubunden, Switzerland
Description: Large specimen with a layer of fine hairlike crystals with sporadic clumps of white crystals imbedded within, on a white to gray rocky matrix.
PHYSICAL CHARACTERISTICS OF ACTINOLITE:
Color is usually green.white or gray.
Luster is vitreous.
Transparency: examples are translucent to transparent.
Crystal System is monoclinic; 2/m
Crystal Habits include the flattened prismatic and elongated crystal with a dome-like termination that is actually a two of the four faces of a prism. Also as a fibrous mass (asbestos) and as a fibrous and very compact mass (nephrite jade).
Cleavage: is perfect in two directions at close to 60- and 120-degree angles.
Fracture is splintery to uneven.
Hardness is 5.5 - 6.
Specific Gravity is approximately 2.9 - 3.3 (very slightly above average for translucent minerals).
Streak is white.
Associated Minerals are quartz, lawsaonite, epidote and glaucophane.
Other Characteristics: the compact nephrite variety is extremely tough and is actually stronger than steel.
Best Field Indicators are toughness (nephrite jade), fibrosity (asbestos), typical green color, crystal habit and hardness.
PHYSICAL CHARACTERISTICS OF ADULARIA: (orthoclase)
Color is off-white, yellow, or shades of red, orange to brown.
Luster is vitreous to dull if weathered.
Transparency crystals are usually opaque, may be translucent or rarely transparent.
Crystal System is monoclinic; 2/m
Crystal Habits include blocky or tabular crystals. Crystals have a nearly rectangular or square cross-section with slightly slanted dome and pinacoid terminations. Twinning is common. (see above). A psuedo-orthorhombic or psuedo-trigonal variety, found in alpine veins is called adularia, and forms more flattened tabular crystals.
Cleavage is good in 2 directions forming nearly right angled prisms.
Fracture is conchoidal or uneven
Hardness is 6
Specific Gravity is approximately 2.53 - 2.56 (average)
Streak is white.
Associated Minerals are quartz, plagioclase feldspars, micas, garnets, tourmalines and topaz.
Other Characteristics: some crystals may show opalescence and are called moonstone.
Best Field Indicators color, lack of striations, cleavage, twinning if present and occurrence.
Fracture: conchoidal
Hardness: 6 Orthoclase
Luster: Vitreous
Occurrence: Actinolite is commonly found in metamorphic rocks, such as contact aureoles surrounding cooled intrusive igneous rocks. It also occurs as a product of metamorphism of magnesium-rich limestones.
Adularia forms in intrusive and extrusive igneous, and metamorphic rocks.
Specific Gravity: 2.7
Streak: white
Variety: Actinolite is a relatively common mineral in some metamorphic rocks. A variety of actinolite is composed of microscopically fibrous crystals (asbestos or amianthus) and is called byssolite. Other varieties are nephrite, which is one of the two minerals called jade.
Adularia is orthoclase form under low temperature and commonly refer to as moonstone.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Weight
10.82 ozDimension Notes
Dimension taken at widest pointsLocation
Location
Drawer
far rightShelf
middle shelf, middle shelfWall
South wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Scott LonganDate
September 19, 2009Location
Container
RightDrawer
3rd ShelfShelf
RightCabinet
Case #42Wall
South wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
Permanent