Black tourmaline with albite, smoky quartz, hyalite, and an aquamarine

Locale: Erongo Mountain, Namibia

Approx dimensions: 3.25 x 3 x 1.75"

Approx weight: 417g

This large glossy black tourmaline, known as schorl, is accompanied by smaller schorl crystals, smoky quartz, and albite. Some of the smaller schorls have mercedes terminations. It's unclear to me if the main schorl is a single crystal or some product of twinning, but it is a large blocky piece with an offset split through the middle. Erongo schorl typically has very high luster as seen in this piece, though it is somewhat obscured by some thin colorless mineral growth on the surface.

This specimen also features a very small faint blue aquamarine beryl with a nice six-sided prism crystal. The aquamarine is perched atop irregular opaque white mineral on the specimen, which is albite, a type of feldspar commonly associated with black tourmaline. The albite is typically not well-formed, but an aggregate of small shard-like pieces, with some pieces of smoky quartz mixed in.

Colorless hyalite coats parts of the albite. Hyalite is a form of opal, which in turn is part of the broader quartz family. It was deposited on the specimen in a later stage of growth. Hyalite displays botryoidal growth (bunches of “grape-like” round crystals) with a glossy high luster like a layer of bubbles. I think it looks like mermaid caviar! Hyalite can appear fluid with formations that look like the splash from a drip frozen in place, or as if the edge has been peeled up from the surface like a tutu.

UV reactivity Hyalite is so strongly UV reactive that you can see it in sunlight. Under indoor lighting it is pale yellow to golden in color, but turns visibly greenish yellow when exposed to the UV in sunlight. 395nm UV fluoresces a strong green, with an icy blue undertone. Best viewed in darker conditions. 365nm UV fluoresces a strong yellowish-green color, generally visible even in bright lighting. No phosphorescence detected.