Almandine

Almandine

Chemical Formula:  Fe₃Al₂Si₃O₁₂

Chemical Composition:  Aluminum, Iron, Silicon, Oxygen

Crystal System:  Cubic (isometeric)

Class:  Silicates

Mineral Group:  Garnet

Crystal Habit:  Trapezohedral, dodocahedral

Hardness:  7 — 7.5

Density/Specific Gravity:  3.93 — 4.30

Refractive Index:  1.770 — 1.820

Double Refraction:  None

Dispersion:  0.027

Absorption Spectra:  617, 576, 526, 505, 476, 462, 438, 428, 404, 393

Colour:  Brownish red, red, blackish red, red with violet tint

Pleochroism:  None

Transparency:  Transparent to translucent

Lustre:  Vitreous (glass like appearance)

Luminescence:  Inert

Cleavage:  None

Fracture:  Irregular/uneven

Assigned Planet:  Pluto

Additional Zodiac Stone:  Leo

Countries:  Deposits found in Austria, Brazil, Czech Republic, India, Magagascar, Sri Lanka, Tanzania, USA, Zambia, Zimbabwe

Notes:  There are more Almandine gemstones faceted and used in jewellery than any other gemstone categorised in the garnet group

 

almandine

Attribution: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

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