This year in Tucson I was able to pick up a specimen of connellite on cuprite, something that I have been after for a couple of years. I am fascinated by the numerous blue specimens associated with copper, mostly as oxidation products. Azurite is probably the best known blue copper mineral; however, there are a host of others. I have been trying, slowly, to document some of these minerals in my small collection by offering postings on this blog. So, the search for connellite. And, in keeping with my theme at 2015 Tucson (see the previous postings on Show Reports] I was searching for specimens under the price of a measly five bucks.
Massive cuprite with two areas of fibrous blue connellite. Width of specimen 2 cm. Collected Bisbee, Warren District, Cochise County, Arizona.
Cheap---probably---but I like to think frugal! Much more frugal than Bob Jones in his Rock and Gem articles (later a book). I purchase minerals, not for an office display nor a case at the local rock show, but to learn as much as possible about the species and then “write it up” for this blog or a club newsletter. One of my goals in life is to continue, “till the end,” to be a life-long learner. So, spending something in four figures would put a crimp on purchasing 200 other specimens---my learning curve would bottom out. Strange---perhaps, but this life–long learning is a passion and helps keep me intellectually alive. As I am fond of saying, life is good.
In the end, it is not the years in your life that counts,
It’s the life in your years. A. Lincoln.
Connellite is a pretty rare mineral, or at least a very uncommon hydrous copper chloro-sulfate. MinDat lists 278 different localities for the occurrence of connellite; however, there seems to be only a few places where the rockhound might have a chance of locating a specimen (assuming you could get on the property). In 1995 Anthony and others wrote “One fist-sized specimen from Bisbee probably contains half of the connellite known in the world.”
This rare secondary mineral [Cu19(SO4)(OH)32Cl4-3H2O] is found in the oxidized zones of copper deposits with Bisbee being a prime example of its occurrence. It has a deep blue to royal blue color, a vitreous luster, a hardness of 3 (Mohs), and occurs as beautiful tiny blue tufts to flattened fibrous layers. These small crystals are mostly translucent. Its most common associated mineral is cuprite but also other secondary copper minerals such as azurite, brochantite, caledonite and malachite. Any observed fracture is splintery.
Photomicrographs of fibrous connellite on cuprite. Width of patch ~4 mm.
Photomicrograph of fibrous connellite on cuprite. Width of patch ~3 mm.
There is a solid solution between connellite and a very rare nitrate termed buttgenbachite [Cu19(NO3)2(OH)32Cl4-2H2O], It would be very difficult for me to distinguish between the two minerals based on observable physical properties. For an in-depth discussion of this solid solution series see Hibbs and others (2006).
Anthony, J.W., S.A. Williams, R.A. Bideaux, R.W. Grant, 1995, Mineralogy of Arizona (Third Edition): The University of Arizona Press, Tucson.
Hibbs, D.E., P. Leverett and A. Williams, 2006, Connellite from Bisbee, Arizona: A single-crystal x-ray study: Axis, v. 2. No. 2.