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Huge Kyanite Crystal on Quartz

The Mineral kyanite




Kyanite is one of the most attractive blue minerals in nature. It sometimes exhibits intense shades of blue, or even multiple shades with color zoning in a single crystal. The color of Kyanite, combined with its well-formed and sometimes large crystals, make this mineral appreciated by both novice and expert collectors alike. The luster of Kyanite from certain localities is sometimes enhanced by oiling specimens or applying them with synthetic lubricants. Legitimate dealers should disclose this practice if they are selling treated Kyanites.

Kyanite is strongly anisotropic, meaning it has a different hardness depending on the angle. In fact, it is the most well-known anisotropic mineral. The vertical hardness of Kyanite ranges from 4.5 to 5.5, and horizontal hardness from 6 to 7. Kyanite is named from the Greek term cyanos, which means deep blue, alluding to the typical color of this mineral.
Chemical Formula Al2SiO5
Composition Aluminum silicate
Color Light to dark blue, indigo-blue. Sometimes multicolored with different shades of blue or white, or with color streaks or stripes. A frequent habit is a deeper colored blue streak running through the center of a crystal. Less commonly colorless, white, gray, green, orange, or black.
Streak Colorless
Hardness 4.5 - 7
Crystal System Triclinic
3D Crystal Atlas
(Click for animated model) 
Crystal Forms
and Aggregates
Most often in long and slender bladed crystals. Also in bladed crystal groups, radiating, in veins, reticulated, and in flattened tabular crystals. Rarely twinned in v-shaped butterfly twins.
Transparency Transparent to translucent
Specific Gravity 3.5 - 3.7
Luster Vitreous
Cleavage 1,1;2,1
Fracture Splintery
Tenacity Brittle
In Group Silicates; Nesosilicates
Striking Features Different direction hardness and color.
Environment In metamorphosed schists and gneisses. Also in granite pegmatites.
Rock Type Igneous, Metamorphic
Popularity (1-4) 2
Prevalence (1-3) 2
Demand (1-3) 2

Kyanite ON EBAY
OTHER NAMES
Cyanite Old spelling for Kyanite that was commonly used through much of the 19th and early 20th centuries.
Disthene

POLYMORPHS
Andalusite

USES
Kyanite is an important collectors mineral due to its beautiful color and ease of obtaining. It is also used as a minor blue gemstone.

NOTEWORTHY LOCALITIES
A classic Kyanite locality is Pizzo Forno, Ticino, Switzerland, where beautiful bladed crystals were found in matrix with Staurolite. Brazil has produced what are arguably the best examples of this mineral, with several important localities. Deep blue crystals in very large crystal sizes are well-known Barra do Salinas, Minas Gerais. Interconnected crystal groupings come from São José da Safira, Doce valley, Minas Gerais; and interconnected, dark gray crystal sprays from Ribeirão das Folhas, Minas Novas, Jequitinhonha valley, Minas Gerais. Gemmy crystals with a distinctive blue vein in the center come from Vitória da Conquista, Bahia, Brazil.

In Russia, good Kyanite crystals in matrix have come from Borisovskie Sopki, Plast, Chelyabinsk Oblast. Nepal has been producing transparent Kyanite of exceptional blue color since 1995. According to the Nepalese mining department, four small-scale Kyanite mines are in operation in Daha and Suneri in Jajarkot and Barah of Aachham districts.

Large, deeply-colored teal crystals have been found in the Umba Valley, Kenya; and unusual orange crystals, sometimes even as v-shaped twins, have recently come from Nani, Loliondo, Arusha Region, Tanzania.

In the U.S., Connecticut has several localities where Kyanite has come from, and the Judds Bridge locality, near Roxbury, Litchfield Co. is especially of note. In Pennsylvania, Kyanite can be found in the Wissahickon Schist at Prospect Park, Ridley Township, Delaware Co. North Carolina has an abundance of Kyanite occurrences, with the Spruce Pine area in Mitchell, Avery, and Yancy Cos. being especially prolific.

COMMON MINERAL ASSOCIATIONS
Quartz, Almandine, Biotite, Staurolite, Andalusite, Albite

DISTINGUISHING SIMILAR MINERALS
The habits of Kyanite make it very easy to distinguish from other minerals.


kyanite PHOTOS
 
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