Name/Title
CreediteEntry/Object ID
2009.62.121Description
Chemical Composition: Hydrated Calcium Aluminum
Crystal System: Monoclinic System
Description: Common Name: Creedite
Chemistry: Ca3Al2SO4(F, OH)-2H2O , Hydrated Calcium Aluminum Sulfate Hydroxide Fluoride
Class: Sulfates
Location: Chihuaha, Mexico
Description: About three-quarters of the specimen is a cluster of translucent to transparent prismatic crystals varying in color from dull white to gray to burnt orange. The remaining portion has a black, opaque, tightly grouped area of crystals that extend outwardly from their relative center.
PHYSICAL CHARACTERISTICS:
Color is white, colorless and purple.
Luster is vitreous.
Transparency crystals are transparent to translucent.
Crystal System is monoclinic; 2/m
Crystal Habits include prismatic crystals with a dome termination whose top edge is slanted with respect to length. Also acicular crystals in radiating groups.
Cleavage is perfect in one direction.
Fracture is uneven.
Hardness is 4.
Specific Gravity is approximately 2.7+ (average for translucent minerals)
Streak is white.
Associated Minerals are limonite, cassiterite, adamite and vanadanite.
Other Characteristics: color if present is unevenly distributed through the crystals.
Best Field Indicators are crystal habit, associations and locality.
Fracture: uneven
Hardness: 4 Flourite
Luster: Vitreous
Occurrence: It is a product of intense oxidation of ore deposits
Creedite is a rather rare sulfate found as an accessory to highly oxidized ore bodies. It can be confused with cobalt-rich adamite when its color is purple. It lacks adamite's luster, though, and adamite's dome termination is not slanted, as creedite's is. Creedite's purple color is attractive and its crystal form is unique, making creedite a nice mineral collection addition
Rock Type: Sedimentary
Specific Gravity: 2.7
Streak: whiteCollection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
3-1/2 inDepth
3-1/2 inLength
4 inWeight
1.16 ozLocation
Location
Container
CenterDrawer
BottomShelf
Left, LeftWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Steve MillerDate
January 26, 2010Location
Drawer
2nd from rightShelf
2nd left shelf, 2nd left shelfWall
West wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Scott LonganDate
September 26, 2009Category
Permanent
