Mindat Logo

Collecting at the Blue Crystal Mine

Last Updated: 30th May 2011

The minerals of this area occur in a block that was down-thrust on the crest of an anticline. The fault runs for 16 miles along the anticline. The anticline was formed by swelling of gypsum and salt of the Paradox formation. The swelling deformed the rock into an anticline as sediment acted like plastic being pushed out of shape by the swelling of the salt and gypsum. The fault is off set by 3800 feet in many places.


The fault is the boundry between the light and dark areas at the far end of the pit. It is filled with large blocks of rubble and fine grain powdered dust and is about 10 feet wide at the top and tapers thinner lower in the picture.

The azurite and other copper minerals were deposited by copper rich fluids that came from the intrusive deep below. These fluids would mix with the saline/brine water closer to the surface. The mixing of these fluids caused the copper mineralization to precipitate out in the form of cuprite, native copper, azurite and malachite filling seams, cracks, voids, and as replacement of other minerals like calcite. In a few really rare cases, the copper minerals also replaced human and rodent bones. (Rock & Mineral Magazine; Utah Issue; vol. 68, No. 6, Nov/Dec 1993)

The mineralization was deposited in Dakota formation sandstone (Cretaceous).



This private mine is a great joy to collected at. Many great specimens can be collected with a moderate amount of effort. Digging in the already worked sand and clay will produce world-class specimens. It started as an underground mine and later was worked as an open pit.


Besides azurite and malachite there are many other copper minerals found in the area. All the crystallized minerals are micro or slightly larger and including aurichalcite, barite, calcite, chalcocite, chalcopyrite, chrysocolla, clinoclase, conichalcite, copper, cornwallite, covellite, cuprite, digenite, djurleite, enargite, goethite, kaolinite, olivenite, psilomelane, pyrite, sphalerite, tennantite, tenorite, tyrolite, and wulfenite.

Our group has found a few of these minerals in recent collecting expeditions including pyrite crystals to 3mm and what I think is brochantite (not on the list of known minerals from this location) crystals to <1mm. Cuprite is common surrounding seams of azurite/malachite. Rarely, native copper can be found in thicker cuprite seams.
I collected at the last working face for a short time and found velvet malachite, massive cuprite, small blebs of native copper, and nothing else.


Pic 1

Pic 2



Azurite concretions nick-named blue berries are very common in this area. They are nodules, usually of solid azurite. Commonly the larger nodules will be mixed with malachite making beautiful specimens. These nodules from from <¼ inch to over 5 inches.

Pic 1

Pic 2



Pic 1

Pic 2






Smaller sizes tend to be solid and have no crystal structure on the outside. Larger ones, over 1 inch, may form hollow cavities with micro azurite crystals on the inside. The most sought specimens are crystallized on the exterior with crystals reaching ¼”. In the prime of collecting in the early 1990's, the mine owner recalled pulling specimens out with many 6cm crystallized rosettes in clusters on matrix. Material of this quality is found today but it is thought to still exist in an area to deep to economically retrieve.




Pic 1

Pic 2

Pic 1

Pic 2




Often over looked is the beauty of the malachite which is very abundant here. A good cleaning with an ultrasonic cleaner or a mini-pressure washer will do wonders for the malachite.


Pic 1

Pic 2








Article has been viewed at least 13415 times.

Comments

In order to leave comments to this article, you must be registered
Mineral and/or Locality  
Search Google  
Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
Current server date and time: October 24, 2014 07:04:57
Mineral and Locality Search
Mineral:
and/or Locality:
Options
Fade toolbar when not in focusFix toolbar to bottom of page
Hide Social Media Links
Slideshow frame delay seconds