Excellent smoky quartz pair with hyalite

Locale: Erongo Mountain, Namibia

Approx dimensions: 3.25 x 2.25 x 2"

Approx weight: 189g

** Loose piece on underside

This is one of my favorite specimens of Erongo hyalite because of its blocky smoky quartz crystals with exquisite horizontal striations. This thing really shows off in a light box (please someone professional at mineral photography buy this).

Smoky quartz from the Erongo region is typically a quite dark brown-black color, with lower clarity due to natural inclusions, and a flat surface luster caused by etching. It grows sculptural blocky or elongated crystals with nice striations. This piece has two main crystals with deep color, excellent clarity, and some high-luster faces providing windows into the interior. The crystals are perched atop a base of several partial points and shard-like broken crystal pieces.

Smoky quartz gets its dark coloration from trace elements that tint dark when the quartz is exposed to natural radiation. Don’t worry, smoky quartz can't expose you to radiation—even if the hyalite turns "radioactive" green under UV light.

Hyalite is a form of opal, which in turn is part of the broader quartz family. Related minerals commonly grow together because they have similar requirements for growth: in this case, the availability of silica that is the basis for the quartz family. Growing conditions that initially produced quartz changed, and a later generation of growth deposited the less common hyalite on the underside of the specimen.

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 away from the quartz like a tutu. This specimen has an interesting lattice-like formation of small colorless needles that have the same fluorescence as the hyalite—green in the core with icy blue needles poking out.

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. This specimen displays the dual-tone fluorescence especially well! 365nm UV fluoresces a strong yellowish-green color, generally visible even in bright lighting. No phosphorescence detected.

Loose piece: There is a shard of smoky quartz on the underside that is loose and will move around (you may hear a faint 'tink' sound like porcelain!). It is firmly wedged between crystals and doesn't seem in danger of falling out.