Name/Title
Bladed CalciteEntry/Object ID
2009.62.76Description
Chemical Composition: FeCO3
Crystal System: Tetragonal System
Description: Common Name: Siderite
Chemistry: FeCO3, Iron Carbonate.
Group: Carbonates
Location: Owyhee County, Idaho
Description: Large scalloped crystals, white at the base accending to a translucent yellow to brown on the leading edges. The matrix is a white snowy color and texture.
PHYSICAL CHARACTERISTICS:
Color is gray, yellow, yellowish brown, greenish-brown, reddish brown and brown. Some specimens show an iridescence probably caused by surface alteration to goethite.
Luster is vitreous to pearly or silky in some specimens.
Transparency: Crystals are usually translucent or virtually opaque.
Crystal System is trigonal; bar 3 2/m.
Crystal Habits are commonly curved rhombohedrons that are sometimes flattened to appear bladed, rarely scalahedral. Many aggregate forms are also found such as botryoidal, sphericules (sphaerosiderite), concretionary, stalactitic, vein-filling and earthy.
Cleavage is perfect in 3 directions forming rhombs.
Fracture is conchoidal to uneven.
Hardness is fairly variable going from 3.5 - 4.5.
Specific Gravity is 3.9+ (relatively heavy)
Streak is white.
Other Characteristics: Becomes magnetic when heated, effervesces slightly in contact with strong acids or with warm acids.
Associated Minerals include iron sulfides and quartz, cerussite, ankerite, dolomite, goethite, cryolite, limonite, barite, pyrite and sphalerite.
Best Field Indicators are crystal habit, slight reaction to acids, cleavage, color and higher than average density
Fracture: conchoidal
Hardness: 4 Flourite
Luster: Vitreous
Occurrence: Siderite is commonly found in hydrothermal veins, and is associated with barite, fluorite, galena, and others. It is also a common diagenetic mineral in shales and sandstones, where it sometimes forms concretions. In sedimentary rocks, siderite commonly forms at shallow burial depths and its elemental composition is often related to the depositional environment of the enclosing sediments.
Specific Gravity: 3.5-4.5
Streak: white
Variety: Siderite is roughly the equivalent of calcite but with iron replacing the calcium. The iron has little effect on most structural properties such as cleavage and crystal form; but does effect properties such as density, color, hardness and electro-chemical properties. Siderite is fairly easy to distinguish from calcite by its higher specific gravity and hardness and less vigorous reaction to acids. It can be difficult to distinguish from dolomite however.Collection
RAGM Mineral CollectionAcquisition
Accession
2009.62Source or Donor
Museum Collection of MineralsAcquisition Method
DonationDimensions
Height
8-1/2 inWidth
4 inLength
12 inDimension Notes
Dimension taken at widest pointsLocation
Location
Display Case
FS-4-BRoom
Frieda Smith HallBuilding
Crater Rock MuseumDate
January 4, 2024Location
Container
RightDrawer
BottomShelf
Right, RightWall
South wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Steve MillerDate
January 15, 2010Location
Shelf
bottom of case #42, bottom of case #42Wall
south wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
scottDate
September 19, 2009Location
Container
Right / RearDrawer
BottomShelf
RightCabinet
Case # 31Building
Freida Smith HallCategory
Permanent