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The Garnet Minerals


Pyrope garnet in eclogite from Shell Beach, California. (more below)
Deep-red garnet of the pyralspite group
Photo (c) 2005 Andrew Alden, licensed to About.com (fair use policy)

Pyrope is one of the aluminum garnets, along with almandine and spessartine forming the "pyralspite" group. (more below)

Its ideal composition is Mg3Al2(SiO4)3. Almandine and spessartine have iron (Fe) and manganese (Mn), respectively, instead of the magnesium (Mg). As chromium (Cr) replaces aluminum (Al), pyrope becomes the blue-green knorringite.

The garnets in this eclogite specimen are partially altered from the severe metamorphism that gives rise to the rock type, so they don't show good crystal form (for that, see the grossular or andradite pictures). Analyses show that they have a high Fe content so they are not pure pyrope, which is known for ite fiery red color. The field of view is about 3 centimeters across.

Particular varieties of pyrope have special names. Bohemian garnet ranges from yellowish red to deep red. Cape ruby or South African ruby comes from the diamond-bearing kimberlites and is a clear ruby color.

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