Name/Title
SideriteEntry/Object ID
2009.62.100Description
Chemical Composition: FeCO3
Crystal System: Tetragonal System
Description: Common Name: Siderite
Chemistry: FeCO3, Iron Carbonate.
Group: Carbonates
Location: Clackamas County, OR
Description: Small nodular crystals with a druzy covering, brown in color on a dark brown rocky matrix.
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.
Rock Type: Sedimentary
Specific Gravity: 3.9+
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
Width
5-1/4 inDepth
2-1/4 inLength
3-3/4 inWeight
1.37 ozLocation
Location
Display Case
FS-5-ARoom
Frieda Smith HallBuilding
Crater Rock MuseumDate
January 3, 2024Location
Container
LeftDrawer
Bottom / Back RowShelf
Right, RightWall
South wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Steve MillerDate
January 22, 2010Location
Drawer
5th from rightShelf
right bottom front, right bottom frontWall
South wallRoom
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Wendy MondryDate
September 25, 2009Location
Container
LeftDrawer
Top ShelfShelf
LeftCabinet
Case #32Wall
EastBuilding
Freida Smith HallCategory
Permanent