Moldavite

Moldavite: a Natural Glass belonging to the Tectites group, made up by 60-70% of Silicon, 10% of Aluminum and, for the rest, of alkalis and various oxides. Amorphous, hardness 5.0-5.5 on the Mohs scale; density 2.34-2.46 g/cm³; n = 1.48 to 1.52. From transparent to semi-transparent, it is found in the medium-dark green, yellowish green, brownish green and grayish green colors.

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