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.
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Massive cuprite with two areas of fibrous blue
connellite. Width of specimen 2 cm. Collected Bisbee, Warren District, Cochise
County, Arizona.
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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.
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Photomicrographs of fibrous connellite on cuprite. Width of patch ~4 mm.
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Photomicrograph of fibrous connellite on
cuprite. Width of patch ~3 mm.
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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).
REFERENCES
CITED
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.