Cyclosilicates

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Tourmaline #1 PPL

Tourmaline thin section

(Mineral group name), from Singhalese turamali, a term originally applied to zircon and other gems by jewelers of Ceylon. Formula: (Na,Ca)(Mg,Li,Al,Fe2+)3Al6 (BO3)3Si6O18(OH)4 System: Trigonal Color: Pale brown...