Complex Sphalerite crystals in a pocket of Dolomite (rock) from Lockport,
New York.
Another crystal of
Sphalerite from the Lockport Dolomite. This crystal displays exsolution of
Chalcopyrite. The crystal is nestled among a bed of Dolomite crystals.
The light yellow crystal in the bottom right is part of a Calcite scalenohedron.
A
blue cube of Fluorite atop of a Sphalerite Matrix. The Sphalerite displays
a typical complex crystal structure. This specimen is from Tennessee.
The backside is shown in this image and illustrates the broken surface of the
Sphalerite. The very reflective face is a cleavage plane.
This close-up image begins to show the resinous luster of the Sphalerite.
A deep green Sphalerite from the Iron
Cap Mine, AZ. The specimen measures about 2" from left to right. (MM
0586)
Sphalerite in
Dolomite (Lockport Dolomite), Niagara Falls, NY
Sphalerite on
Johansonite from the Iron Cap Mine, AZ.
CHEMISTRY - ZnS Zinc sulfide
CRYSTALLOGRAPHY - Cubic
CRYSTAL GROWTH AND HABITS - The common forms are tetrahedral and dodecahedral with many complex and distorted growths. Sphalerite can also be botryoidal, stalactitic, and coarse to fine grained massive.
COLOR AND OTHER OPTICAL PROPERTIES - The color of Sphalerite ranges from colorless to dark brown, gray to black. It is commonly brown, yellow, reddish or greenish.
HARDNESS - 3.5 - 4
SPECIFIC GRAVITY - 3.9 - 4.1
LUSTER - Resinous to sub metallic
STREAK - Light yellow
BREAKABILITY - Very good {011} cleavage (dodecahedra - six sided), the fracture is uneven to conchoidal. Sphalerite is brittle.
OCCURRENCE - Sphalerite forms in a variety of environments including low to high temperature hydrothermal, as well as in coal and limestone deposits.
ASSOCIATED MINERALS - Galena, Chalcopyrite, Marcasite, Pyrite, Fluorite, Barite, Quartz and Calcite.
MINERAL NAME - From the Greek for treacherous in reference to its confusion with Galena.