Topaz - Minas Gerais, Brazil | Ref.434

Clear topaz from Minas Gerais

This topaz from Minas Gerais, Brazil, from an old collection, consists of an isolated crystal ranging from clear to almost colourless, displayed on an acrylic base. Its compact form is defined by broad flat faces and a short prismatic development.

Several lateral faces show longitudinal striations. The transparency is not uniform: some areas are clear, while others appear more diffuse or cloudy. Small reddish-brown marks can also be seen within the crystal depending on the viewing angle and lighting.

Crystal morphology

Topaz crystallises in the orthorhombic system. Its crystals commonly develop as prisms of varying length, with striations running parallel to the main axis. In this piece, the width of the crystal and its limited height give it a compact, stocky outline, unlike topaz crystals with more elongated prisms.

Origin: Minas Gerais, Brazil

Minas Gerais is one of Brazil’s principal regions associated with topaz mining. The state is particularly known for the diversity of its crystals and gem minerals. The documented origin of this piece is limited to Minas Gerais, with no further information regarding the mine or exact locality where it was collected.

Mineralogical information

With the chemical formula Al₂SiO₄(F,OH)₂, topaz is an aluminium silicate containing fluorine and hydroxyl groups. It belongs to the nesosilicate group. Its lustre is generally vitreous, and it reaches a hardness of 8 on the Mohs scale.

Dimensions and presentation

The stone measures 40 mm long × 28 mm wide × 34 mm high. These dimensions refer only to the mineral. Its total weight is 96 g including the acrylic base.