Rare Faceted Brucite
Gem-quality transparent blue brucite is a very rare, very soft and heat-sensitive magnesium hydroxide (Mg(OH)2) with a Mohs hardness of approximately 2.5–3.0 and perfect cleavage. Brucite was named in 1824 in honor of the first person to describe the species: Archibald Bruce, an American mineralogist, physician, and editor of the American Mineralogical Journal.
Recently the Carlsbad laboratory received for identification services a transparent greenish blue stone weighing 3.09 ct and measuring 9.74 × 9.71 × 5.98 mm (see above). Microscopic observation revealed numerous scratches and abrasions on the surface, as well as strong doubling, some needles, and a large fracture. Standard gemological testing yielded a specific gravity of 2.37. Refractive index was not measured for fear of damaging this soft and fragile stone. A uniaxial optic character was observed with a polariscope and optic figure sphere. Raman spectroscopy confirmed the gem’s identity as brucite. Worldwide, this was the second brucite examined by GIA.
