Name/Title
GypsumEntry/Object ID
2009.62.232Description
Chemical Composition: Sulfates
Crystal System: Monoclinic System
Description: Common Name: Gypsum (twin bladed golden)
Chemistry:CaSO4*2H2O
Class: Sulfates
Location: Las Salinas Halite Mine, Otume, South of Pisco, Peru
Description: A large block with the entire top layer of solid crystals. The crystals are golden, twinned with a few crystals larger than others. Matrix is layered sandstone.
PHYSICAL CHARACTERISTICS:
• Color is usually white, colorless or gray, but can also be shades of red, brown and yellow.
• Luster is vitreous to pearly especially on cleavage surfaces.
• Transparency crystals are transparent to translucent.
• Crystal System is monoclinic; 2/m
• Crystal Habits include the tabular, bladed or blocky crystals with a slanted parallelogram outline. The pinacoid faces dominate with jutting prism faces on the edges of the tabular crystals. Long thin crystals show bends and some specimens bend into spirals called "Ram's Horn Selenite" Two types of twinning are common and one produces a "spear head twin" or "swallowtail twin" while the other type produces a "fishtail twin". Also massive, crusty, granular, earthy and fiberous.
• Cleavage is good in one direction and distinct in two others..
• Fracture is uneven but rarely seen.
• Hardness is 2 and can be scratched by a fingernail.
• Specific Gravity is approximately 2.3+ (light)
• Streak is white.
• Associated Minerals are halite, calcite, sulfur, pyrite, borax and many others.
• Other Characteristics: thin crystals are flexible but not elastic, meaning they can be bent but will not bend back on their own. Also some samples are fluorescent. Gypsum has a very low thermal conductivity (hence it's use in drywall as an insulating filler). A crystal of Gypsum will feel noticeably warmer than a like crystal of quartz.
• Notable Occurances include Naica, Mexico; Sicily; Utah and Colorado, USA; and many other locallities throughout the world.
• Best Field Indicators are crystal habit, flexible crystals, cleavage and hardness.
- See more at: http://www.galleries.com/Gypsum#sthash.BhWscISt.dpuf
Fracture: Uneven
Hardness: 2 Gypsum
Luster: Pearly
Rock Type: Sedimentary
Specific Gravity: 2.3+
Streak: WhiteCollection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Width
18 inDepth
4 inLength
23 inLocation
Category
PermanentMoved By
Curtis GardnerDate
May 25, 2023Notes
Added current locationLocation
Container
centerDrawer
bottom tierShelf
west side, west sideWall
centerRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Wendy MondryDate
January 6, 2010Location
Container
centerDrawer
bottom tierShelf
west side, west sideWall
centerRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Wendy MondryDate
January 6, 2010Location
Cabinet
I-7 FrontWall
NorthBuilding
Storage (old gift shop upstairs)Category
Permanent
