Topaz

This huge, clear topaz crystal weighing 5.5 kg has a perfect and sharp crystal shape (orthorhombic crystal system) with a diamond-shaped cross-section. It was mined from a prominent Brazilian pegmatite deposit. Its chemical composition is aluminium fluorine silicate.

This specimen has been on continuous display in successive mineral exhibitions since its acquisition in 1941 through an exchange with Warner & Geiger, a Californian company supplying mineral specimens and noted for its pegmatite minerals.