Name/Title
EnargiteEntry/Object ID
2014.1.14Description
Chemical Composition: Al(OH)3
Crystal System: Hexagonal System
Description: Common Name: Enargite
Chemistry: Cu3AsS4
Group: Sulfides
Location: Butte, Montana
Description: Small specimen with blocky and tabular black crystals without unformity.
Physical Charateristics:
•Color is gray to black.
•Luster is metallic.
•Transparency: Crystals are opaque.
•Crystal System is orthorhombic; 2 m m
•Crystal Habits include pseudohexagonal prismatic to blocky or tabular crystals, often terminated by a flat pedion face. Also found massive, granular and in radiating aggregates. Twinning is common and sometimes results in a star shaped cyclic twin called a trilling.
•Cleavage is perfect in two directions, prismatically; distinct in two other directions also prismatically but with different orientations.
•Fracture is uneven.
•Hardness is 3 - 3.5
•Specific Gravity is approximately 4.4+ (average for metallic minerals)
•Streak is black.
•Other Characteristics: crystals are typically striated lengthwise and a tarnish will dull the luster of crystals over time.
•Associated Minerals are quartz, bornite, galena, sphalerite, tennantite, chalcocite, chalcopyrite, covellite, pyrite and other sulfides.
•Notable Occurrences include Butte, Montana, San Juan Mountains, Colorado and at both Bingham Canyon and Tintic, Utah, USA; Sonora, Mexico; Argentina; Chile; Morococha and Cerro de Pasco, Peru and Island of Luzon, Philippines.
•Best Field Indicators are crystal habit, streak, cleavage and associations.
Hardness: 7 Quartz
Rock Type: SedimentaryCollection
RAGM Mineral CollectionAcquisition
Accession
2014.1Source or Donor
Crater Rock Museum (unknown donors)Acquisition Method
GiftDimensions
Height
2-1/8 inWidth
1-1/4 inLength
1-1/4 inLocation
Location
Shelf
CS-I-1Room
Curation StorageBuilding
Crater Rock MuseumDate
February 3, 2024Location
Shelf
5th shelfCabinet
Case# 20Wall
WestBuilding
Freida Smith HallCategory
Permanent
