Colorado Gem & Mineral Co. - Rocks for the Rest of Us

Rock Talk and Information from a Geologist

Welcome to our informational section of our website.  Hopefully you will find out something you needed to know.

Rainbow or Iridescent Quartz In 1950 Dr. C.V. Raman (father of Raman Spectroscopy) published the discovery of a colorless Quartz that exhibits adularescence, or iridescence. It occurs in druse veins emplaced in basalts, and it has also been discovered in Argentina on the slopes of a volcano. Jack has found a good source for very fine specimens from India, and we now offer them on this website. We call it Rainbow Quartz; locality is Madhya Pradesh, India. It is difficult to capture all the colors that a specimen displays in a photo. Rest assured that these specimens will show neon color in nearly all the crystals on a specimen, changing as the specimen is viewed from different angles. The colors are due to polysynthetic twinning in the crystal; and this is not the same as interference pattern rainbows seen in fractures of clear quartz. The cause of this structure in basalt related quartz has not been determined.Amethyst discovered by Jack Lowell in Uruguayan Basalts exhibits this optical phenomenon and is named Lowell Effect Amethyst by the Gemological Institute of America. We have cut amethysts that display adularescence, the cut stones have a rim of multicolored or white zones around the table of the gems.  It is subtle.  We have also cut a few India colorless quartz that shows bright neon colors similar to opal.  Inquire or check our gemstones.

Chrysanthemum Stones Most of the Chrysanthemum Stones in China are from Hubei Province, and there are many "embellished" C. Stones from Hunan Province, they occur in a grayish limestone and the patterns are very faint irregular shapes with edges similar to what pinking shears do to cloth, a zig zagging pattern.  The material is darkened by putting black color on the whole rock after outlining the pattern in pencil.  Then the design is painted on with white paint.  Immersing these in water will show a loss of contrast between the rock and design. Genuine Chrysanthemum Stones (Hubei Province) have patterns made of solid calcite/strontianite/quartz mixture shapes, often petal shaped, and often resembling flowers.  Recurrent themes are "Palm trees" and "fireworks."  There have been huge assembled stones up to four feet tall, they have been manufactured by placing real patterned stones together in a synthetic black medium that is very close to the carbonaceous limestone of the genuine stones. The collecting areas are currently being covered by a new reservoir and the stones will become very rare now. There are also some rare ornamental stones from Igneous rock in Japan that are fashioned into beautiful presentations with small polished tablets of the rock with custom bases with graceful design. These are called Suiseki.

I send a Chrysanthemum Stone from Hubei Province, China to Bob Downs at the Univ. of AZ and the white material is a mixture of Strontianite and Calcite.  Almost all the literature says Celestine instead of Strontianite.  Most of the Chrysanthemum Stones in China are from Hubei Province, and there are many "embellished" C. Stones from Hunan Province, they occur in a grayish limestone and the patterns are very faint irregular shapes with edges similar to what pinking shears do to cloth, a zig zagging pattern. The collecting areas are currently being covered by a new reservoir and the stones will become very rare now.

The flowerstone is

Strontianite 83%

Quartz 10%

Calcite 7%


 


 

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