Name/Title
SphaleriteEntry/Object ID
2014.1.83Description
Chemical Composition: (Zn, Fe)S
Crystal System: Cubic or Isometric S
Description: Common Name: Sphalerite
Chemistry: (Zn, Fe)S, Zinc Iron Sulfide
Group: Carbonates / Sulfides
Location: Elmwood, Tenn.
Description:
PHYSICAL CHARACTERISTICS OF SPHALERITE:
Color is typically black but can be brown, yellow, reddish, green, and less commonly white or colorless.
Luster is adamantine or resinous or submetallic to earthy in massive forms.
Transparency crystals are transparent to translucent.
Crystal System is isometric; bar 4 3m
Crystal Habits can be complicated with the rhombic dodecahedron, tetrahedron and combinations of these having cubic and tristetrahedron faces giving the crystals multiple faces of often indistinct forms. To add more confusion to the indistinct crystals, twinning is common and sometimes pervasive. Massive forms are common and can be granular, earthy, botryoidal, concretionary and fibrous. An aggregate of botryoidal crusts with layers of wurtzite and galena is called "Schalenblende" is sometimes cut and polished as an ornamental stone.
Cleavage is perfect in six directions forming dodecahedrons.
Fracture is conchoidal, but rarely seen because of frequent cleavage.
Hardness is 3.5-4
Specific Gravity is approximately 4.0 (heavier than average, but light when compared to most metallic minerals)
Streak is yellow to light brown (unusually light colored for a normally dark mineral).
Other Characteristics: Striations on tetrahedral faces, triboluminescent (meaning it may glow if crushed), an index of refraction of 2.37 - 2.42, a dispersion (fire) of 0.156 and finally sphalerite is pyroelectric (meaning that it forms a slight electrical charge when heated or cooled).
Associated Minerals almost always include galena, pyrite, fluorite, chalcopyrite, quartz, calcite, magnetite, pyrrhotite and many others.
Best Field Indicators are crystal habits, streak, cleavage, high luster, softness and twinning.
Fracture: uneven to conchoidal
Hardness: 4 Fluorite
Luster: Metallic
Occurrence: Sphalerite forms in sulfide ore veins in all rock classes. Sources of high quality crystals include: Freiberg, Saxony, and Neudorf, Harz Mountains of Germany;
the Lengenbach Quarry, Binntal, Valais, Switzerland, has produced colorless crystals; Horni Slavkov (Schlaggenwald) and Pribram, Czech Republic; from Rodna, Romania; transparent green to opaque black Madan, Smolyan Province, Rhodope Mountains, Bulgaria; transparent crystals in the Aliva mine, Picos de Europa Mountains, Cantabria [Santander] Province, Spain; in England, from Alston Moor, Cumbria; at Dalnegorsk, Primorskiy Kray, Russia; in Canada - Watson Lake, Yukon Territory & Gord Cowie at Hudson Bay Mining and Smelting processes Sphalerite in Flin Flon, Manitoba; in the USA - the Tri-State district including deposits near Baxter Springs, Cherokee County, Kansas; Joplin, Jasper County, Missouri and Picher, Ottawa County, Oklahoma, from the Elmwood mine, near Carthage, Smith County, Tennessee, and the Eagle mine, Gilman district, Eagle County, Colorado; in Mexico, from Santa Eulalia and Naica, Chihuahua, and Cananea, Sonora; Huaron, Casapalca; Huancavelica, Peru
Rock Type: Igneous
Specific Gravity: 2.7
Streak: yellow to light brow
Variety: Sphalerite is one of the very few minerals that has a total of six directions of cleavage. If all of them were to be perfectly cleaved on a single crystal it would form a rhombic dodecahedron. Identifying all six directions in a single cleaved crystal is quite difficult due to the multiple twinning and the many directions. Only the fact that there is abundant cleavage at different directions can easily be seen in most cleaved specimens.
Sphalerite can be difficult to identify because of its variable luster, color, abundant but obscured cleavage and crystal habits. So difficult was sphalerite for miners to distinguish from more valuable minerals such as galena, acanthite and tetrahedrite, that they named it sphalerite which is Greek for treacherous rock and blende is German for blind or deceiving.Collection
RAGM Mineral CollectionAcquisition
Accession
2014.1Source or Donor
Crater Rock Museum (unknown donors)Acquisition Method
GiftDimensions
Width
8-3/4 inDepth
5 inLength
9-1/2 inDimension Notes
Dimension taken at widest pointsLocation
Location
Display Case
FS-5-ARoom
Frieda Smith HallBuilding
Crater Rock MuseumCategory
ExhibitMoved By
Ian C.Date
January 29, 2025Notes
Major mineral groups installationCategory
PermanentMoved By
Curtis GardnerDate
May 25, 2023Notes
Added current location
