Name/Title
RiebeckiteEntry/Object ID
2014.1.36Description
Chemical Composition: Al(OH)3
Crystal System: Hexagonal System
Description: Common Name: Riebeckite
Chemistry: Na2(Fe, Mg)3Fe2Si8O22(OH)2
Group: Silicates
Location: Unknown
Description: Small, rounded specimen with a quartz matrix and dark green needle-like crystals covering most of the specimen.
Physical Charateristics:
•Color is usually dark blue to black.
•Luster is vitreous or silky in fibrous forms.
•Transparency: Crystals are translucent.
•Crystal System is monoclinic; 2/m.
•Crystal Habits include slender prismatic to acicular, often aggregated crystals, columnar, granular and fibrous, asbestiform masses. A moss-like aggregate habit has been described when found in some igneous rocks.
•Cleavage: is perfect in two directions at 56 and 124 degree angles.
•Fracture is splintery to uneven.
•Hardness is 5 - 6.
•Specific Gravity is approximately 3.2 - 3.4 (average to slightly above average).
•Streak is blue-gray.
•Other Characteristics: Weakly pleochroic and crystals are striated lengthwise.
•Associated Minerals are nepheline, quartz, almandine, aegirine, feldspars, micas and hematite.
•Notable Occurrences include Socotra Island, South Yemen; Transvaal, South Africa; Schirmeck, Germany; Langesund, Norway; Krivoi Rog, Ukraine; Hamersley Range in Western Australia; Scotland; Madagascar; Quincy, Massachusetts; St Peter's Dome, El Paso County, Colorado; California; Oregon and Cumberland Hill, Rhode Island, USA.
•Best Field Indicators are crystal habit, color, streak, cleavage and hardness.
Hardness: 7 Quartz
Rock Type: SedimentaryCollection
RAGM Mineral CollectionAcquisition
Accession
2014.1Source or Donor
Crater Rock Museum (unknown donors)Acquisition Method
GiftOther Names and Numbers
Other Number
Other Number: 78.62.247Dimensions
Height
2-7/8 inWidth
1-1/2 inLength
1-3/4 inLocation
Location
Display Case
FS-11Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Curtis GardnerDate
December 27, 2023
