UVAROVITE

UVAROVITE (a green Garnet)

Uvarovite is a rare and valuable member of the Garnet mineral group. It is named after Russian statesman and mineral collector Count Sergey Semenovitch Uvarov. Uvarovite is known for its deep green color and exceptional crystal formations, making it a popular choice among specimen collectors and jewelry enthusiasts.

Composition of Uvarovite

Uvarovite is a green calcium chromium silicate mineral with the formula Ca₃Cr₂(SiO₄)₃. Its green color is primarily due to the presence of chromium, which acts as a chromophore. Uvarovite is one of the few naturally occurring minerals with high chromium concentrations. Uvarovite is the only true chromium Garnet; other forms, such as Andradite and Grossular, may have a deep green color due to chromium impurities and can sometimes be mistakenly labeled as Uvarovite. The green variety of Andradite is known as Demantoid. The green variety of Grossular is known as Tsavorite. Uvarovite forms a solid solution series with both Andradite and Grossular. Uvarovite is the chromium end member, with chromium replaced by aluminum to form the Grossular end member or by iron to form the Andradite end member.

Uvarovite typically forms as small, dodecahedral crystals or as drusy aggregates, which means it consists of a coating of tiny crystals on a host rock. The crystals are often very small, measuring only a few millimeters, but they can be quite striking due to their vibrant green color and sparkling appearance.

Characteristics

The color is usually deep, emerald-green, but it can range from a vivid green to a slightly yellowish or bluish-green shade. Uvarovite crystallizes in the Isometric Crystal System, Hexoctahedral Crystal Class. Its crystals often form dodecahedra with 12 faces with geometrically equal pentagonal shapes. These crystals can be quite small, typically measuring a few millimeters. Luster ranges from vitreous to subadamantine. Hardness is 6.5 – 7 on the Mohs Scale. This hardness makes it durable enough for use in jewelry and contributes to its overall durability as a gemstone.

Uvarovite typically forms as a result of hydrothermal or metamorphic processes. It is commonly found in serpentinite, a rock composed mainly of serpentine minerals derived from the alteration of ultramafic rocks (such as peridotite) in the presence of water. The chromium-rich fluids from the serpentinization process can infiltrate fractures and cavities within the serpentinite, forming uvarovite crystals.

Uvarovite’s vibrant green color and sparkling appearance make it desirable as a gemstone. It is often used in jewelry, particularly in pendants, earrings, and brooches. Due to its limited availability and smaller crystal size, uvarovite is more commonly used as an accent stone than a centerpiece gemstone.

Noteworthy Localities of Uvarovite

Uvarovite is a rare mineral with limited occurrences. The largest crystals of this mineral come from Outukumpu, Finland, where they come as individual crystals often embedded in a matrix. The most prolific Uvarovite and type locality is the Saranovskii Mine in Sarany, in the Ural Mountains of Russia, where it occurs as small emerald-green crystal grouping, often covering a matrix. Small crystals are found in Val Malenco, Lombardy, Italy, and in the Kop Krom mine, Erzerum, Turkey. In the United States, Uvarovite occurs in California in Jackson, Amador County; Jacksonville, Tuolumne County; and near Livermore, Alameda County. It has also been discovered in North Carolina and Pennsylvania.

By Bill Jones, Sidewinder Minerals

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