Montana Garnet

Montana Garnet is almandine garnet found in the placer gravels of Montana, USA, frequently in the same stream deposits that yield the state's well-known sapphires. It is typically a deep, slightly purplish red.

Most crystals are small to medium, transparent to translucent, and rounded by stream transport. While much Montana garnet is collected as a byproduct of sapphire and gold mining, clean pieces are faceted into attractive American-origin gems.

The stone appeals to collectors who value its US source and its association with Montana's gem gravels.

Almandine is the classic garnet of regional metamorphism, crystallizing in schists and gneisses from aluminum- and iron-rich sediments subjected to heat and pressure. Montana's mountain belts contain abundant such metamorphic and igneous source rocks.

As these rocks weathered, the durable garnets were carried into stream and placer gravels along drainages such as those of the Missouri River system and the famous sapphire-bearing gravels. There the garnets concentrate with other heavy minerals and are recovered by panning, sluicing, and screening.

Montana Garnet is deep red to purplish-red, often as rounded, water-worn grains, with vitreous luster.

• Hardness: 7-7.5.
• Streak: white.
• Optic character: singly refractive.
• Fracture: conchoidal, no cleavage.
• Density: high (almandine is notably dense).

Its deep red color and high density are diagnostic; single refraction separates it from ruby and red tourmaline. Its rounded shape signals an alluvial origin.

Clean Montana Garnet is faceted into small to medium gems prized for their American origin, and rough is sold to collectors. Lower-grade almandine is widely used as an industrial abrasive in blasting media, waterjet cutting, and sandpaper.

It is durable for jewelry. As a red garnet, it carries metaphysical associations of grounding and vitality, though these are not scientific claims.