|
|
www.mineralgallery.co.za Minerals K-O |
|
|
Kyanite |
||
Name
Kyanite
Chemistry
Al2 SiO5, Aluminum Silicate
Uses
As mineral specimens and in the manufacture of spark plugs.
Color
Usually blue but can also be white, gray or green. Color is often not consistent throughout the crystal and can be blochy or in streaks.
Hardness
Hardness is approximately 4.5 when scratched parallel to the long axis of the crystal and approximately 6.5 when scratched perpendicular to or across the long axis.
Specific gravity
3.5-3.7
The aluminum silicate mineral kyanite is used in the manufacture of spark plugs, porcelain, and other heat-resistant ceramics.
Its name is derived from the Greek kyanos, meaning blue, for its long-bladed, usually blue crystals of the triclinic system.
Kyanite, found in metamorphic rock such as gneiss, schist, and in granite pegmatite, is considered an indicator of deep-seated, regional metamorphism of clay-rich sediments.
The luster is vitreous to pearly, specific gravity is 3.5-3.7, and cleavage is perfect in one direction.
Kyanite is an attractive mineral that has a near sapphire like blue color in some especially nice specimens.
Kyanite has a unique characteristic in that it has a wide variation in hardness, in the same crystal. The hardness of kyanite is approximately 4.5 when scratched parallel to the long axis of the crystal and approximately 6.5 when scratched perpendicular to or across the long axis.
Other minerals usually have variable hardness on different crystal faces due to a different concentration and oreintation of the atoms in the structure. Diamond is one such mineral, a fact gem cutters take advantage of often.
