|GOLD HILL ORE CHUTE|
I recently noted the occurrence of the occurrence of adamite, a zinc arsenate hydroxide, in my miniscule collection of minerals from Gold Hill, Utah. A couple of readers (wow, I didn’t know if anyone read these blogs or not ) confirmed the mammillary structures are goethite pseudomorphs after smithsonite! Another reader suggested that the tiny acicular spray in the vug might be olivenite, a copper arsenate hydroxide [Cu2(AsO4)(OH)] that is common at Gold Hill.
In examining tiny pieces of minerals in my collection box I did notice “some blue” color. I may be color blind with red-green-brown but can spot blue or purple (but I get them mixed up). Initially I thought the streaks were linarite as a crust rather than small clusters of crystals. Linarite is a secondary lead copper sulfate hydroxide that is found in the oxidation zone of ore bodies containing lead. It has that beautiful azure blue color.
|CRUST OF AZURITE WITH BOTRYOIDAL HABIT (TOUGH TO SE WITH THIS POWER). LEFT TO RIGHT IS ~6.2 MM.|
However, under high power of my binocular microscope I was able to notice a botryoidal habit rather than tiny crystals common to linarite. This revived my brain cells and caused me to pull out the acid and I noticed the blue mineral “fizzed” indicating a carbonate. So, I am now “guessing” (that is what paleontologists do with mineral identification) that the blue streak is common azurite, a carbonate of copper [Cu3(CO3)(OH)2)], with a beautiful azure blue color. So it goes.
By the way, the Rockpick Legend Co. in Salt Lake City has a wonderful collection of Gold Hill minerals and a great web site at:
|PHOTOMICROGRAPH OF AZURITE CRUST FROM GOLD HILL. tHE FIELD OF VIEW IS ~2.4 MM.|