Blue blood.
Gem Silica, Meaning, Properties, and Facts
Chalcedony · SiO2Mohs 6.5 to 7Copper blue
Gem silica is translucent blue to blue-green chalcedony colored by chrysocolla, a copper mineral, and it is the most valued form of chalcedony. Below: its properties, where it is found, how it differs from chrysocolla, how to spot a fake, how to care for it and the meaning people give it.
What is gem silica
Gem silica is chalcedony, the same microscopic quartz as agate, that grew while soaked in copper-rich water, so chrysocolla, a soft blue copper silicate, ended up spread evenly through the hard silica. The result has chrysocolla's color with the hardness of quartz and a glowing, see-through look. It is also sold as chrysocolla chalcedony, and Geology.com's gem silica guide shows good examples of gem silica stone.
Gem silica properties
Gem silica properties are mostly chalcedony's: hard, tough and slightly porous, with copper supplying the blue (data on Mindat's gem silica page):
| Mineral | Chalcedony colored by chrysocolla |
|---|---|
| Chemistry | SiO2 with copper silicate (chrysocolla) |
| Color cause | Copper, in chrysocolla spread through the silica |
| Hardness | About 6.5 to 7 on the Mohs scale |
| Crystal system | Trigonal (microcrystalline) |
| Luster | Waxy to glassy |
| Specific gravity | About 2.6 |
| Main localities | Arizona copper mines; smaller amounts from other copper districts |
| Water safe | Quick rinse only |
| Sun safe | Room light yes; avoid heat |
Where gem silica is found
Gem silica is found in the weathered upper zones of copper deposits, where rain and groundwater break down copper ore and carry copper and silica into cracks. The classic source is the copper mines of Arizona, especially the Inspiration Mine in the Globe and Miami district, and smaller amounts come from other copper districts. It forms in thin seams inside large mines, so fine pieces are scarce.
Gem silica vs chrysocolla
Gem silica vs chrysocolla comes down to hardness and glow. Plain chrysocolla is opaque and soft, around 2 to 4 on the Mohs scale, so it scratches easily and soaks up water; gem silica is chrysocolla locked inside chalcedony, so it is translucent and about 6.5 to 7. The same copper color, two very different stones.
How to tell if gem silica is real
How to tell if gem silica is real takes a good light. Real gem silica glows from inside with a saturated blue to blue-green color, while dyed blue chalcedony or quartz often looks too bright or shows color pooled in cracks. Other blue stones get mixed up with it: plain chrysocolla is opaque and soft, turquoise is opaque and often veined, and larimar, a pectolite from the Dominican Republic, is softer with white, wavy patterns. Natural blue chalcedony from other deposits is paler and more lavender.
Gem silica care: water and sun
Gem silica care is mostly about the copper mineral inside it. A quick rinse in cool water is fine, but do not soak it, since chrysocolla-rich spots are porous, and keep it away from heat, acids and harsh cleaners; normal room light will not hurt it. The water safe crystals guide covers soaking in general. Gem silica contains copper, so treat it like the copper minerals in toxic crystals: handling a polished stone is fine, but do not grind it, breathe the dust or put it in drinking water.
Gem silica meaning
Gem silica meaning, in crystal lore, is calm and clear communication, borrowed from chrysocolla, which is sold as a stone for speaking your truth. That is belief, not chemistry, and gem silica benefits sit in the same box. The name chrysocolla is old: it comes from the Greek words for gold and glue, and Theophrastus used it around 315 BC for a material used to solder gold (more on Wikipedia).
Gem silica price and value
Gem silica price and value depend on color, translucency and size. The most valued stones are evenly saturated, bright blue to blue-green and see-through, without matrix or cracks, and large clean pieces are rare. Cut stones are often sold by the carat, while opaque or patchy material costs much less.
Gem silica for sale
Gem silica for sale on geoslut arrives in drops: each piece is one of one, photographed in daylight and labeled with its locality, and the list hears about every drop first.
Gem Silica FAQ
Is gem silica the same as chrysocolla?
Gem silica is not the same as plain chrysocolla: it is chalcedony colored by chrysocolla, so it is harder and translucent.
Is gem silica toxic?
Gem silica is not toxic to handle, but it contains copper, so do not swallow it, breathe its dust or make drinking water with it.
Is gem silica rare?
Gem silica is rare in fine quality, because it forms only in thin seams in the weathered zones of copper deposits.
What is the hardness of gem silica?
The hardness of gem silica is about 6.5 to 7 on the Mohs scale, far harder than plain chrysocolla.
Sources
- Gem silica, Geology.com
- Gem silica, Mindat
- Chrysocolla, Wikipedia