Smoky quartz cluster with black tourmaline and hyalite

Smoky quartz cluster with black tourmaline and hyaliteLocale: Erongo Mountain, Namibia Approx dimensions: 4. 5 x 3. 5 x 3" Approx weight: 488g ** Loose piece on underside The top of this specimen is a smoky quartz cluster, perched on an aggregate of black tourmaline and irregular shards of smoky quartz, coated in hyalite. The largest smoky quartz crystal in this cluster is 3" with lighter color, good clarity, and a faint phantom. The black tourmaline (schorl) is mostly poorly developed, but there is one

Locale: Erongo Mountain, Namibia

Approx dimensions: 4.5 x 3.5 x 3"

Approx weight: 488g

** Loose piece on underside

The top of this specimen is a smoky quartz cluster, perched on an aggregate of black tourmaline and irregular shards of smoky quartz, coated in hyalite. The largest smoky quartz crystal in this cluster is 3" with lighter color, good clarity, and a faint phantom. The black tourmaline (schorl) is mostly poorly developed, but there is one small well-formed crystal nestled in the smoky quartz crystal, featuring the classic trigonal 'Mercedes' termination characteristic of Erongo material.

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 elongated and angular points with nice striations.

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

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 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. The hyalite on this specimen may be "hidden" on the bottom, but it is lush with very clear large botryoidal hyalite. There are two spheres that are white at the center like snowballs trapped in the hyalite.

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.

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.