Almandine Garnet

These garnet grains are fragments of some large garnet crystals found in the Adirondack Mountains of New York. So technically, they're pieces of garnet (probably the variety almandine) rather than "garnets." Real crystals of garnet have a distinctive round shape (like this crystal of grossular garnet), but they have no cleavage, unlike minerals like calcite or fluorite, and when you crush them these ragged pieces are the result. (That makes garnet a good mineral abrasive.) Clear whole gem-quality garnets are rather rare.

Almandine is one of the aluminum garnets, along with pyrope and spessartine (the "pyralspite" group). Its composition is Fe₃Al₂(SiO₄)₃, with the silica groups (SiO₄) being isolated, not linked in chains or sheets as in most silicate minerals. Pyrope and spessartine have magnesium and manganese, respectively, instead of the iron (Fe).

Garnet is a family of minerals that includes a few green species (including grossular and andradite), but most garnets range in color from salmon-orange to dark ruby red. If you took the whole Earth, threw away the iron core, and turned the rest of it into a single giant stone, it would be a garnet in composition.

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