Garnet Physical Properties

Garnet Physical Properties loose sale price & Garnet Gemstone Information

  • Crystal system: isometric; 4/m bar3 2/m

  • Crystal habit: commonly forms as rhombic dodecahedrons, trapezohedrons, or a mixture of these two forms. Rarely as hexoctahedrons. Also as coarse or fine massive granular.

  • Specific gravity: 3.4 - 4.3 (almandine 3.95-4.32, pyrope 3.53-3.87, spessartine 3.80-4.25, andradite 3.70-4.18, grossular 3.56-3.71 and uvarovite 3.40-3.90)

  • Index of refraction: 1.72-1.94 (almandine 1.75-1.83, pyrope 1.73-1.77, spessartine 1.79-1.81, andradite 1.86-1.94, grossular 1.72-1.80 and uvarovite 1.74-1.87)

  • Birefringence: 0.000-0.005 (almandine 0.000, pyrope 0.000, spessartine 0.000-0.004, andradite 0.000-0.005, grossular 0.000-0.005 and uvarovite 0.000-0.005)

  • Pleochroism: none

  • Hardness: 6.5 - 7.5

  • Color: Garnets occur in all colors except blue. Almandine is typically a deep red-violet, also can be red, brownish-red and brownish-black. Pyrope usually a blood-red, also dark red, purplish-red, orangish-red and pinkish-red. Spessartine can be orange, reddish-orange, red, reddish-brown, yellowish-brown and brown. Andradite occurs in yellowish-green, green, greenish-brown, gray and black. Grossular can be colorless, gray, many shades of yellow and green, also pink, red, brown and black. Uvarovite is a dark green.

  • Luster: vitreous to resinous, can occur with chatoyancy due to minute asbestiform inclusions of pyroxene or amphibole, yielding a four-ray star when fashioned into a cabochon gem.

  • Transparency: transparent to opaque

  • Cleavage: none

  • Fracture: conchoidal, somewhat brittle

  • Streak: white