Spinel

The derivation of the name of spinel is uncertain. It may come from the latin word Spina for 'spine' or 'thorn', because the stone is often found as sharp crystals. Since medieval times, it has also been known as the 'Balas Ruby', after Balascia (today Badakhsan), a region of North-East Afghanistan that for many years was a source of fine specimen of spinel.

Spinel is found in a wide range of color due to the presence of various impurities,and is transparent to almost opaque.

Red spinel is colored by chromium and iron. It is the most popular, although for many years it was thought to be a variety of Ruby. Sometime when it is cut in to cabochon may show 4-rayed or 6-rayed stars. There are different color of spinel we found in the Earth. The coloring agents of spinel are iron, chromium, vanadium.

According to the color of spinel they are named different:-

  1. Flame spinel     :- Its color is bright orange to orange-red. In the past it was sometimes called rubicelle.
  2. Balas Spinel     :- It is pale red variety. It is falsely called Balas Ruby.
  3. Pleonaste         :- Its color is dark green to blackish. It is also called Ceylonite. It is opaque spinel. Its density is 3.63 - 3.90
  4. Hercynite          :- Its color is dark green to black. Its density is 3.95.
  5. Gahnite            :- Its color is blue, violet or dark green to blackish. Its density is 4.00 - 4.62. It is also known as Zinc spinel.
  6. Gahno Spinel   :- Its color is Blue to dark blue or green. Its density is 3.58-4.06.
  7. Picotite             :- Its color is brownish, dark green or blackish. Its density is 4.42. It is also called Chrome Spinel.

DEPOSIT

The most important location where spinel is found are Burma(Myanmar, near Mogok), Cambodia and Srilanka(Ratnapura). Other deposits are found in Afghanistan, Australia, Brazil and Madagascar, Nepal, Nigeria, Tadzhikistan, Tanzania, Thailand and the united States(New Jersey).

PROPERTIES

Species   Spinel
Variety   Spinel
Chem Comp  MgO. AI2 O3 (magnesium Aluminium Oxide)
Crystal System   Cubic
Color  All color also Color changing types.
Cause of COLOR    Red and Pink - chromium
                               Blue - Iron
  Violet - Iron + Chromium
Luster     Vitreous
Hardness    8
S.G.   3.58 to 3.64 (Mean - 3.60)
Optic Sign    None
R.I. Range   1.712 to 1.80
Birefringence   None

INCLUSION

Inclusion in spinel are Octahedron, Crystals, Ghost-like feathers, Zircon Haloes, Rutile Needles.

SIMULANTS

Synthetic Spinel, Zircons, Aquamarine, tourmaline, Cobalt glass, Ruby, Sapphire, Garnet, Ghanite are the simulants of Spinel.

 

Raw Stone
After Cutting