Hydroxyapophyllite

HydroxyapophylliteLocale: N'Chwaning II Mine, South Africa Approx dimensions: 2. 25 x 1. 5 x 1" Approx weight: 95g 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: 2.25 x 1.5 x 1"

Approx weight: 95g

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.

The matte brown mineral coating the specimen is lizardite, which often grows in small spots along the junctions of the hydroxyapophyllite crystal. It especially highlights structure of the hydroxyapophyllite crystals of this piece. The largest crystal (just shy of 1cm) has a different shape from the rest: instead of two symmetrical faces on the edges it has one very large face and one that barely exists.

Calcite druzy glitters through the lizardite and covers the back of the specimen. The calcite has also formed clusters of small scalenohedral crystals. The heavy dark matrix 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 with a strong flashlight.

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