Spinel

Category  :  Mineral
Hardness  :  8
Gravity  :  3.54-3.63
Reflection  :  1.71
Color  :  Various, red to blue to mauve. Dark green, brown. Black
Chemical formula  :  MgAl2O4
Crystal system  :  Isometric
Major varieties  :  Red Spinel, Blue Spinel

True spinel has long been found in the gemstone-bearing gravel of Sri Lanka and in limestones of the Badakshan province in nowadays Tajikistan and of Mogok in Burma. Recently gem quality spinels were also found in the marbles of Luc Yen (Vietnam), Mahenge and Matombo (Tanzania), Tsavo (Kenya) and in the gravels of Tunduru (Tanzania) and Ilakaka (Madagascar). Spinel is found as a metamorphic mineral, and also as a primary mineral in rare mafic igneous rocks; in these igneous rocks, the magmas are relatively deficient in alkalis relative to aluminium, and aluminium oxide may form as the mineral corundum or may combine with magnesia to form spinel. This is why spinel and ruby are often found together.

Red Spinel

Red spinel is fairly similar to ruby; the red color fluoresces slightly in bright light, but much less than ruby. Being singly refractive, it is not pleochroic. It is generally given a mixed, oval or round cut, alternatively a square or rectangular, step or trap cut.

Blue Spinel

The finest specimens have a bright blue color comparable to that of some sapphires and are very attractive, lustrous and transparent. Most blue spinels are a deep dull color tending to sooty gray, albeit with a violet tinge, and their luster and transparency are marred by a touch of cloudiness. Blue spinel is mainly found in the gem gravels of Sri Lanka and rarely in Burma.


Click to enlarge

Click to enlarge

Click to enlarge

Click to enlarge

Click to enlarge

Click to enlarge

 

Our Location Map

Location map