Posted by: frank Post Reply
This stone may very well be dyed but the zoned color is in no way unusual for metamorphic rocks. When certain metamorphic conditions prevail rocks can be in a state of slight melting.In that state it is very common for like minerals in the rock to migrate and aggregate. Metamorphism is usually a partial process which makes ids for geologists a chore. In addition the rock is often subjected to another metamorphosis , usually a down grade metamorphosis which results in zoned crystal aggregations. That phenomena you are seeing in the stone is identical to some zoning. As to the color , blue is a rare calcedony color until recently. Indonesians have found tons of calcedony colored by copper.It is found as replacement of petrified wood, casts, and comes in many shades and is often mixed with opal giving it a slight opal like quality because the intimately mixed opal and calcedony are imiscible, they try to stay segregated and as a segregated medium the light path becomes the type that produces opalescence. Beautiful mystery.
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