Hydroxyapophyllite

HydroxyapophylliteLocale: N'Chwaning II Mine, South Africa Approx dimensions: 2 x 1. 5 x 1. 25" Approx weight: 145g This specimen features hydroxyapophyllite crystals with lizardite and calcite on matrix. Properly called "hydroxyapophyllite (K)," hydroxyapophyllite is a variety of apophyllite that is typically colorless. It more frequently grows cubic crystals, but these specimens from the renowned N'Chwaning Mines region form tabular square crystals similar to

Locale: N'Chwaning II Mine, South Africa

Approx dimensions: 2 x 1.5 x 1.25"

Approx weight: 145g

This specimen features hydroxyapophyllite crystals with lizardite and calcite on matrix. Properly called "hydroxyapophyllite-(K)," hydroxyapophyllite is a variety of apophyllite that is typically colorless. It more frequently grows cubic crystals, but these specimens from the renowned N'Chwaning Mines region form tabular square crystals similar to wulfenite, and can be colorless to semi-translucent white with inclusions.

This piece is covered with around two dozen hydroxyapophyllite crystals. The coffee-brown staining may be iron; the lighter brown mineral coating the specimen is lizardite, which often grows in small spots along the junctions of the hydroxyapophyllite crystal. Calcite has formed clusters of small scalenohedral crystals, and coats the specimen under the brown. Under UV light the calcite fluoresces from under the hydroxyapophyllite crystals, giving them a faint red glow—try it in a dark room.

The minerals are on a heavy dark matrix that is likely manganese-based; the N'Chwaning mines were established to extract the rich manganese ore in the area.

UV reactivity Visible calcite fluoresces and phosphoresces moderate red under 365 nm UV light. It can cause the hydroxyapophyllite crystals growing over it to glow a faint red—try it in a dark room.

** Brittle warning! Hydroxyapophyllite specimens are somewhat delicate and may shed pieces; limit handling.