The Earth Story

Cuprite This gem specimen of copper oxide, the mineral cuprite (Cu2O) was found at the Tsumeb mine in Namibia. 

Stunning cuprite While we have shared a micromount sample of the bright red copper oxide also known as ruby copper before (see http://tinyurl.com/kzlp9ky), this 2cm macro crystal is the finest quality there is. Since it crystallises in the cubic system, it tends to form similar shapes to diamonds, in this case a complex series of octahedral twins. It is a spectacular secondary mineral, with bright lustre, that originates in the oxidised zone of copper sulphide deposits, where groundwater and hydrothermal fluids have enriched the deposit by removing elements such as silica, a process known in the minig biz as supergene enrichment (which front loads cashflow in order to repay the debt used to finance the capital costs of the operation). Localities include Chile, the Democratic Republic of Congo, the Russian Urals and Namibia (Tsumeb mine). Larger crystals have been faceted for collectors. Our past posts on twinned crystals:http://tinyurl.com/me9rpxh http://tinyurl.com/mvbojuj http://tinyurl.com/l8yba54,http://tinyurl.com/ntdtdb6, http://tinyurl.com/nr7cq6n,http://tinyurl.com/kp6nluf, http://tinyurl.com/nr7cq6nand http://tinyurl.com/lr9rvgf

Once red, then green, now blue

A stunning pair of crystals reveals some of the complex changes that happen in ore deposits as they get uncovered by erosion and their primary minerals (usually dull grey or silvery sulphides) are gradually altered into a succession of secondary ones as the ore is percolated by circulating waters of varied chemistry that move through all the surface layers of our planet. The 1.4 x 1.3 x 0.8 cm piece from France started as the copper oxide mineral Cuprite (see http://bit.ly/1Cbe5f9 and http://bit.ly/1AjbRrW) as oxygenated fluids first altered it, followed by a succession of copper carbonates. It first turned into green Malachite (with some remnants still visible) before changing again into blue Azurite. The final product retains the shape and crystal habit of the original mineral, a process named after the Greek for fake shape and known as pseudomorphosis.

Loz

Image credit: Joe Budd/Rob Lavinsky/iRocks.com

Stunning cuprite While we have shared a micromount sample of the bright red copper oxide also known as ruby copper before (see http://tinyurl.com/kzlp9ky), this 2cm macro crystal is the finest quality there is. Since it crystallises in the cubic system, it tends to form similar shapes to diamonds, in this case a complex series of octahedral twins. It is a spectacular secondary mineral, with bright lustre, that originates in the oxidised zone of copper sulphide deposits, where groundwater and hydrothermal fluids have enriched the deposit by removing elements such as silica, a process known in the minig biz as supergene enrichment (which front loads cashflow in order to repay the debt used to finance the capital costs of the operation). Localities include Chile, the Democratic Republic of Congo, the Russian Urals and Namibia (Tsumeb mine). Larger crystals have been faceted for collectors. Our past posts on twinned crystals: http://tinyurl.com/me9rpxh http://tinyurl.com/mvbojujhttp://tinyurl.com/l8yba54, http://tinyurl.com/ntdtdb6, http://tinyurl.com/nr7cq6n, http://tinyurl.com/kp6nluf, http://tinyurl.com/nr7cq6n and http://tinyurl.com/lr9rvgf Loz Image credit: Wolfgang Hartmann

Cuprite A bright red copper oxide also known as ruby copper, it crystallises in the cubic system, tending to form similar shapes to diamonds such as this octahedron on malachite (3.4 x 2.9 x 2.1 cm) from the Democratic Republic of Congo. It is a spectacular secondary mineral, with bright lustre, that originates in the oxidised zone of copper sulphide deposits, where groundwater and hydrothermal fluids have enriched the deposit by removing elements such as silica, a process known in the mining biz as supergene enrichment (which front loads cashflow in order to repay the debt used to finance the capital costs of the operation). Other localities include Chile, the Russian Urals and Namibia (Tsumeb mine). Larger crystals have occasionally been faceted for collectors. Loz Image credit: Rob Lavinsky/iRocks.com http://webmineral.com/data/Cuprite.shtml http://www.mindat.org/min-1172.html http://geology.com/minerals/cuprite.shtml http://www.minerals.net/mineral/cuprite.aspx

Micro-minerals: Cuprite on calcite.

Mineral collectors with limited funds and space (or tidyness obsessed partners who don't tolerate piles of rocks around the house) often get into micromounting: the collection of small (less than a square inch), cheap (typically less than US$10) samples of minerals that look amazing when magnified. Since large cabinet specimens of many minerals run into the thousands of dollars, this can be a way to accumulate a much broader collection with the disposable funds available, and as the 2mm image shows, visually spectacular.

Only a few hundred of the 5000 or so known minerals occur as larger crystals, so for many varieties micro is the only way to go. Many have 1000+ mineral species, and one person claims to have 80% of mineral species in their collection. The most expensive necessity is a decent (preferably binocular) microscope (US$200-7000, but the lower end will do just fine) with a fibre optic side illumination.

Micromounters are often more interested in the aesthetic and scientific aspects of their specimens, rather than the financial value or showing off spectacular treasure cabinets. Many collect and prepare their own specimens, which are frequently left behind by more commercially inclined seekers as not worth the gathering time (since mineral specimens have to be very carefully separated from the host rock).

For many the real satisfaction lies in the process of gathering, inspecting, cataloguing and exchanging their local minerals. Clubs are a hotbed of swapping, and gatherings often feature a free donation table of samples for beginners to get their eye in. The best way to get into the game is to find a conference or gathering and join in. Like astronomy clubs members are helpful to newcomers sharing their hobby and like nothing better than to share their knowledge and experience. It's a great way to learn some serious mineralogy while admiring beautiful things with a bunch of like minded people.

These lovely red tendrils of cuprite are copper oxide are displaying a crystal habit known as capillary, or threadlike. It is a spectacular secondary mineral, with bright lustre, that originates in the oxidised zone of copper sulphide deposits, where groundwater and hydrothermal fluids have enriched the deposit by removing elements such as silica. It's alternative name is ruby copper, for obvious reasons. Localities include Chile, the Democratic Republic of Congo, Urals and Namibia (Tsumeb mine). Larger crystals have been faceted for collectors.

Loz

Location: Clara mine, Baden-Wurttenberg, Germany. Size 2mm.

Image credit: Gerhard Niceus.

http://www.njminerals.org/micro.html

http://www.baltimoremineralsociety.org/micromounting.html

http://webmineral.com/data/Cuprite.shtml

http://www.mindat.org/min-1172.html

http://geology.com/minerals/cuprite.shtml

http://www.minerals.net/mineral/cuprite.aspx

Stunning cuprite While we have shared a micromount sample of the bright red copper oxide also known as ruby copper before (see http://tinyurl.com/kzlp9ky), this 2cm macro crystal is the finest quality there is. Since it crystallises in the cubic system, it tends to form similar shapes to diamonds, in this case a complex series of octahedral twins. It is a spectacular secondary mineral, with bright lustre, that originates in the oxidised zone of copper sulphide deposits, where groundwater and hydrothermal fluids have enriched the deposit by removing elements such as silica, a process known in the minig biz as supergene enrichment (which front loads cashflow in order to repay the debt used to finance the capital costs of the operation). Localities include Chile, the Democratic Republic of Congo, the Russian Urals and Namibia (Tsumeb mine). Larger crystals have been faceted for collectors. Our past posts on twinned crystals:http://tinyurl.com/me9rpxh http://tinyurl.com/mvbojuj http://tinyurl.com/l8yba54,http://tinyurl.com/ntdtdb6, http://tinyurl.com/nr7cq6n,http://tinyurl.com/kp6nluf, http://tinyurl.com/nr7cq6n and http://tinyurl.com/lr9rvgf Loz Image credit: Wolfgang Hartmann