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 collectors and jewelry enthusiasts.
The chemical formula of uvarovite is Ca3Cr2(SiO4)3, indicating that it is a calcium chromium silicate. 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 that contain high concentrations of chromium.
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 in size, but they can be quite striking due to their vibrant green color and sparkling appearance.
The mineral is usually found in association with other chromium-rich minerals in metamorphic rocks, such as serpentinite or skarn deposits. It is primarily found in several locations around the world, including Russia (where it was first discovered), Finland, Turkey, and the United States.
Uvarovite has been prized for its beauty and rarity since its discovery in the early 19th century. It is often used in jewelry, although its use is somewhat limited due to its small crystal size and relative scarcity. When used in jewelry, uvarovite is typically set in protective settings, such as pendants or brooches, to prevent damage to the delicate crystals.
Due to its rarity and unique green color, uvarovite holds significant value among collectors. Fine specimens of uvarovite can command high prices in the gem and mineral market, especially when they exhibit well-formed crystals with intense green coloration.
In summary, uvarovite is a rare and captivating green mineral belonging to the garnet group. Its distinctive crystal formations and chromium-rich composition make it a sought-after gemstone among collectors and jewelry enthusiasts alike.
Contents
Chemical composition and classification
The chemical composition of uvarovite is represented by the formula Ca3Cr2(SiO4)3. This indicates that it is a calcium chromium silicate mineral. Let’s break down the formula to understand its composition:
- Ca: This represents the element calcium, which is an essential component of the mineral. It provides the calcium ions necessary for the crystal structure.
- Cr: This symbolizes the element chromium, which is the key element responsible for the green color of uvarovite. Chromium acts as a chromophore and imparts the characteristic hue to the mineral.
- SiO4: This group represents the silicate tetrahedron, which is composed of one silicon atom bonded to four oxygen atoms. Silicate tetrahedra are the building blocks of many minerals, including uvarovite. In uvarovite, three of these tetrahedra are bonded to each chromium ion.
Uvarovite belongs to the garnet mineral group, which is a large family of minerals with a common crystal structure. The garnet group consists of various minerals that share a similar arrangement of atoms within their crystal lattice. These minerals often have a general formula of A3B2(SiO4)3, where A and B represent different cations occupying specific sites in the crystal structure.
In the case of uvarovite, the A-site is occupied by calcium (Ca), and the B-site is occupied by chromium (Cr). This classification places uvarovite specifically within the ugrandite subgroup of garnets, which includes other calcium-rich garnet minerals.
To summarize, uvarovite is a calcium chromium silicate mineral belonging to the garnet group. Its chemical formula, Ca3Cr2(SiO4)3, highlights the presence of calcium, chromium, and silicate in its composition.
Physical properties and characteristics
Uvarovite possesses several physical properties and characteristics that contribute to its distinctiveness. Here are some key features of uvarovite:
- Color: Uvarovite is renowned for its deep, emerald-green color. The green hue is primarily caused by the presence of chromium in its crystal structure. The color can range from a vivid green to a slightly yellowish or bluish-green shade.
- Crystal System: Uvarovite crystallizes in the isometric crystal system. Its crystals often form dodecahedra, which have 12 faces with geometrically equal pentagonal shapes. These crystals can be quite small, typically measuring a few millimeters in size.
- Transparency: Uvarovite is typically transparent to translucent, allowing light to pass through its crystal structure. In thin fragments or small crystals, it may appear more transparent, while larger specimens may exhibit some degree of translucency.
- Luster: The mineral has a vitreous to subadamantine luster, giving it a shiny and reflective appearance when polished or viewed under appropriate lighting conditions.
- Hardness: Uvarovite has a relatively high hardness on the Mohs scale, ranging between 6.5 and 7.5. This hardness makes it durable enough for use in jewelry and contributes to its overall durability as a gemstone.
- Density: The density of uvarovite typically ranges from 3.35 to 3.60 g/cm³. This density, combined with its hardness, helps distinguish uvarovite from other green gemstones with similar appearances.
- Cleavage: Uvarovite exhibits no cleavage, which means it lacks any preferred breaking planes or directions within its crystal structure. Instead, it tends to fracture in a conchoidal (shell-like) manner when subjected to external forces.
- Refractive Index: The refractive index of uvarovite ranges from approximately 1.84 to 1.88. This property affects how light is bent or refracted as it enters and exits the mineral, contributing to its brilliance and play of colors.
- Specific Gravity: Uvarovite has a specific gravity ranging from 3.35 to 3.60, indicating that it is heavier than an equal volume of water.
These physical properties collectively contribute to the aesthetic appeal and gemological characteristics of uvarovite. Its vivid green color, combined with its luster and crystal form, makes it an attractive choice for jewelry and mineral collectors alike.
Geology and Occurrence of Uvarovite
Uvarovite is primarily associated with specific geological environments, and its occurrence is relatively rare. Here’s an overview of its geology and occurrence:
Geological Formation: Uvarovite typically forms as a result of hydrothermal or metamorphic processes. It is commonly found in serpentinite, which is 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, leading to the formation of uvarovite crystals.
Occurrence:
- Russia: Uvarovite was first discovered in the Ural Mountains of Russia, specifically in the Saranovskii Mine near Saranovskaya Village. This region remains one of the most significant sources of uvarovite. The Russian uvarovite crystals are often associated with chromite deposits.
- Finland: Uvarovite is also found in the Outokumpu region of eastern Finland. It occurs in chromite-bearing rocks associated with serpentinite and skarn deposits.
- Turkey: Uvarovite has been found in the Eskisehir Province of Turkey. It occurs in serpentinized peridotite rocks in association with chromite and other chromium-rich minerals.
- United States: Uvarovite has been reported in several locations within the United States. In California, it has been found in the Serpentine Belt of the Klamath Mountains. It has also been discovered in North Carolina and Pennsylvania, associated with serpentinite and other ultramafic rocks.
- Other Localities: Uvarovite has been documented in a few other countries, including South Africa, Canada, Norway, and Italy. However, its occurrence in these locations is relatively limited compared to the primary sources mentioned above.
It’s important to note that while uvarovite is a member of the garnet family, it is not as widespread as other garnet minerals. Its occurrence is more localized and confined to specific geological settings where the conditions are favorable for its formation. As a result, uvarovite is considered a relatively rare and sought-after gemstone and mineral specimen.
Uses and Applications
Uvarovite, although relatively rare, finds a few specific uses and applications. Here are some notable ones:
- Gemstone: 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 rather than a centerpiece gemstone.
- Ornamental Purposes: Uvarovite’s unique green hue and crystal formations make it popular among mineral collectors and enthusiasts. It is often sought after for its aesthetic value and incorporated into mineral collections, displays, and ornamental pieces.
- Spiritual and Healing Properties: Like other gemstones, uvarovite is believed to possess spiritual and metaphysical properties. It is associated with properties such as healing, abundance, positivity, and attracting love and harmony. Some individuals use uvarovite for meditation, energy work, and spiritual practices.
- Decorative Inlays: Uvarovite’s rich green color and small crystal size make it suitable for decorative inlays. It can be used to embellish furniture, decorative objects, and even musical instruments, adding a touch of natural beauty and elegance.
- Geological and Scientific Research: Uvarovite, along with other garnet minerals, has significance in geological research and studies. Its occurrence and characteristics provide valuable insights into specific rock formations, hydrothermal processes, and metamorphic environments.
It is important to note that uvarovite’s primary use and demand stem from its rarity, unique color, and aesthetic appeal. However, its limited availability and smaller crystal size compared to other garnets restrict its widespread use in various applications.
Reference Lists
- Mindat.org – Uvarovite: A comprehensive mineral database that includes detailed information on uvarovite, its properties, occurrence, and crystallography. Available at: https://www.mindat.org/min-4125.html
- Uvarovite on Webmineral: Webmineral provides a concise overview of uvarovite, including its chemical composition, crystallography, physical properties, and occurrence. Available at: http://webmineral.com/data/Uvarovite.shtml
- Handbook of Mineralogy – Uvarovite: A detailed reference for mineralogists and researchers, providing in-depth information on uvarovite’s crystallography, chemical composition, physical properties, and occurrence. Available at: http://www.handbookofmineralogy.org/pdfs/uvarovite.pdf
- Gemological Institute of America (GIA) – Uvarovite: GIA offers gemological information on uvarovite, focusing on its gemological properties, grading, and identification. Available at: https://www.gia.edu/gem-encyclopedia/uvarovite
- Gemdat.org – Uvarovite: Gemdat.org provides information on uvarovite’s gemological properties, occurrence, and sources. Available at: https://www.gemdat.org/gem-4125.html
- Pough, F.H. (1996). A Field Guide to Rocks and Minerals. Houghton Mifflin Harcourt: New York. ISBN-13: 978-0395910962.
