Sphalerite is a mineral with a hardness of 4 out of 10 on the Mohs scale of mineral hardness [?]. These Cubicly structured gems are made of zinc sulfide, their full chemical compound being (Zn,Fe)S.

Sphalerite is a zinc iron sulfide mineral formed in an isometric system. It is trimorphous with wurtzite and matraite. All three have the same chemical compound but crystallize in three different forms.

The most common crystal forms of sphalerite are in dodecahedrons and tetrahedrons, elegant three-sided formations, often twinned, and otherwise usually massive, thus looking like brownish-black or cherry-red colonies forming a stark contrast on its host rock, for example white dolomite. It also appears as pseudo-octahedral crystals, often with rounded edges. Layered sphalerite was called "Schalenblende" in German. Crystals vary from transparent to opaque. It can occur as inclusions in the reddish-orange almandine garnet.

Sphalerite has a bright luster which is even diamond-like on cleavage surfaces. Its high refractive index nearly equals that of diamond. It emits a characteristic odor when rubbed across an unglazed porcelain surface, and when dilute hydrochloric acid is added, will produce the smell of "rotten eggs."

It forms complex ores in pegmatitic-pneumatolytic veins where crystallization occurs during hot gaseous activity in late stages of cooling. It is also found in hydrothermal veins associated with galena, marcasite, pyrite, argentite, greenockite, chalcopyrite, barite and fluorite. Pure zinc sulfide is white in powder form. As the iron content increases, the color changes from yellow to brown, red, dark green, and black (marmatite, a variety of sphalerite).

Many of the economically important sources of sphalerite are in hydrothermal areas, such as those in Oberharz, Freiberg, in the Erzebirge, in Schauinsland in the Schwarzwald (Germany); also Bleiberg in Carinthia and Pribram (Czech Republic).

Very important deposits are found in the Tri-state district in the USA (Oklahoma, Kansas, and Missouri), Sullivan (Canada), Broken Hill (Australia), Bleiberg (Austria), Yugoslavia, Raibi (eastern Alps, Italy), and Sardinia (Montevecchio, Monteponi and Campo Pisano).

Sphalerite is also found with pyrite and barite in sedimentary deposits near Meggen in Westphalia.
The most beautiful crystals come from Trepca, Yugoslavia (especially marmatites), Butte, Montana (USA), and Oruro and Potosi (Bolivia). Light-colored crystals, which are unusual for sphalerite, come from Picos de Europa, Santander, Spain. Small but fine transparent crystals in different colors are found in the metamorphic dolomites of the Binn Valley (Valais, Switzerland) and in Italy in Carrara marble. Fine marmatites occur in Bottino (Tuscany, Italy).

Sphalerite mineral is also called "black jack."

The crystal form of sphalerite has a non-metallic resinous luster. The amber-colored variety is called "honey blende" and the red variety is misnamed "ruby blende". The colorless variety is called "cleiophane".

The specific gravity [?] for Sphalerite is 4.09, it's refractive index [?] is 2.36-2.37, and it's double refraction [?] is None.


Sphalerite has an interesting history leading to its name. Being known by the German word "Blende," it was first mentioned by Agricola in the 16th century. "Blende" was used to describe this metal-free, black, or sometimes yellow rock which, because of its heaviness and luster that looked like metal, "blendet und betrugt," "blinded and deceived" the miner into believing it had useful metal content. It was only in the 18th century that the Swedish chemist Georg Brandt discovered a zinc ore in Blende. When this happened, its original "blind-and-deceive" monicker was proven to be unfounded, but a hint of this stayed on in its present name sphalerite, from the Greek word "sphaleros" which means "deceiving."

Industrial Usages

Sphalerite crystal is often difficult to cut because of its perfect cleavage. It is often confused with other yellow gemstones and with colorless diamond. After polishing, some yellow color sphalerite does resemble a canary diamond.

As an important zinc ore, sphalerite mineral is always associated with galena. It often contains rarer metals such as cadmium, indium, gallium, germanium, gold, and silver, which are recovered during smelting.

The annual world production of zinc is about 5.8 million tons, and almost all that is derived from sphalerite.

Technical uses for zinc are in the production of brass and bronze alloys, as an anti-corrosive in the galvanizing of sheet steel and iron, galvanic elements, pigments such as zinc white, lithopone, zinc yellow, and in insecticides. Production of zinc does produce excessive residues which cause nearby rivers and soils to carry excessive levels of heavy metals, a condition which can be alleviated by effective sewage treatment.

You May Also Like...


Almandine: Almandine or Almandite is a member of the Garnet group, and is associated with the planet Pluto. Low quality pyrope is often cataloged and sold as Almandine. Almandine is generally darker than pyrope. Almandine colors vary from red to dark red, purple to purplish red, and even pink. Almandine is valued fairly low at somewhere between $5 and $225 a carat all dependent upon clarity, color, cut, an (read full)

Grossular Garnet

Grossular Garnet: Grossular is a nesosilicate in the Garnet group, with an isometric crystal system. Together with uvarovite and andradite, the three are known as the "ugrandite garnets," an isomorphous series of calcium garnet minerals. It appears with dodecahedral or trapezohedral crystals of various colors; normally characterized by a green color, but also may be colorless, pale green or milky when pure, cinnam (read full)


Unarovite: Uvarovite is a rare, calcium-chromium emerald-green variety of Garnet. Together with grossular (calcium-aluminum) and andradite (calcium-iron), it makes up the series of ugrandite garnets. These three have similar crystal structure and form, but just have different chemical proportions. It occurs in mixed crystals, so there is a partial replacement of some elements by others. It stands out from t (read full)


Pyrope: Pyrope is the iron magnesium and aluminum silicate of the pyrope-almandine series in the Pyralspite group of the Garnet family. Its beautiful deep-red gem quality makes it one of the most popular. Pure pyrope is colorless, but its red color, sometimes very bright, is due to small quantities of chrome in the crystal structure. It appears as dodecahedral or trapezohedral crystals, dark red, usually (read full)


Spessartine: Spessartine is the manganese-aluminum variety of Garnet, belonging to its sub-group of aluminum garnets. Garnets are a group of silicate minerals that all crystallize in the isometric system and have the same chemical formula, but in a diversity of proportions, so garnets show up as different varieties, in a broad range of environments. Spessartine possesses the form typical of garnet crystals, w (read full)



Double Refraction or dr is the ability of a mineral to separate a refracted ray of light into 2 rays. If held over an image or text it will display the object 2x its original size.

Mohs Scale of Mineral Hardness is the standard used to categorize a mineral's ability to resist scratching. It gets its name from Friedrich Mohs, the German geologist who first created the scale.

RI or Refractive Index defines light's ability to move through the mineral or in a general sense, any material.

SG or Specific Gravity is the ratio of the weight of any substance to that of pure water at temperature of 3.98°C(39.2°F) and standard atmospheric pressure. This is important to note when actively seeking these minerals in the wild. Minerals with a higher SG will settle below material with a lower sg over time.