ANDRADITE

Named in 1868 by James Dwight Dana in honor of José Bonifácio de Andrada, Brazilian mineralogist, is a calcium-iron garnet, Ca3Fe2(SiO4)3, is of variable composition and may be red, yellow, brown, green or black.

Value:
The rarest and most valuable garnet gem is the green to yellowish-green variety of the mineral andradite, called demantoid.

The price of garnets is determined by several factors, including color, clarity, carat weight, and cut. Color: Red garnets are the most common, but garnets are available in many colors. Rare colors such as peach, green, colorless, and blue are particularly valuable.

ANDRADITE (GARNET)

USES

With properties that may enhance skin regeneration and elasticity, andradite is sometimes used in skincare regimens to help improve skin health and reduce signs of aging. Andradite garnet is often sought for its potential to increase physical energy and stamina.

MOHS HARDNESS

It is a relatively durable gemstone with a hardness rating of 6.5 to 7.0 on the Mohs scale making it suitable for all types of jewelry, including rings.

LUSTER

The luster of garnets ranges from vitreous to resinous to subadamantine. Colors can be red, brown, yellow, orange, white, green, or black or shades in between.

CHEMICAL COMPOUND

The chemical compound is Ca3Fe2(SiO4)3. This means it is a calcium-iron silicate.

WHERE TO FIND

It can be found in Iran, Italy, the Ural Mountains of Russia, Arizona and California and in Dnipropetrovsk Oblast in Ukraine.

DIAGNOSTIC PROPERTIES

  • Color: Andradite can be many colors, including green, black, yellow, pink, and brown.
  • Luster: Andradite can have a vitreous, resinous, or adamantine luster.
  • Transparency: Andradite can be transparent, translucent, or opaque.
  • Hardness: Andradite has a hardness of about 6.5 to 7 on the Mohs scale.
  • Cleavage: Andradite doesn’t have cleavage, meaning it doesn’t have planes of weakness that make it easy to break.
  • Specific gravity: Andradite has a specific gravity of about 3.8 to 4.2.
  • Crystal system: Andradite crystallizes in the cubic crystal system.
  • Dispersion: Demantoid garnets, a type of andradite, have high dispersion, which means they can break light into its spectral colors more effectively than other gemstones.
  • Inclusions: Inclusions like “horsetail” inclusions in demantoid garnets can enhance the value and visual appeal of andradite.
  • Refractive index: Andradite has a refractive index of about 1.88 to 1.91.