This blog is a electronic museum of my collections of antiquities, ethnographic, first editions, retro pottery from the 1950's to early 1970's, shell, mineral and gemstone samples,fossils and other wonderful things! Comments are welcome on the objects including advice which will add to my own wonderment and knowledge.

Thursday, July 17, 2014

Mineral Specimen: Atacamite Crystal Cluster

Chemical Formula: Cu2Cl(OH)3
Provenance: La Farola Mine, PERU
Size and Weight:275 grams. Approx 10 x 5 x 2.5 cm

Atacamite is polymorphous with botallackite, clinoatacamite, and paratacamite. Atacamite is a comparatively rare mineral, formed from primary copper minerals in the oxidation or weathering zone of arid climates. It has also been reportedas a volcanic sublimate from fumarole deposits, as sulfide alteration products in black smokers and as alteration of ancient bronze and copper artefacts. It occurs in association with cuprite, brochantite, linarite, caledonite, malachite, chrysocolla and its polymorphs.

Mineral Specimen: Black Aegirine Acmite Crystal on Orthoclase

Chemical Formula: NaFeSi2O6
Provenance: Mt. Malosa, Zomba Valley District, Malawi, AFRICA
Size and Weight: 13 grams. Approx 4 x 3 x 0.8 cm

Usually found as a long, thin, prismatic or bladed crystal/s, with a pointed pyramid on top (clinopinacoidal), and very often embedded in a matrix. Fibrous masses, radiating sprays, and interlocking thin prismatic crystals are also common. May also be in reticulated masses and in grainy aggregates embedded in a matrix. Crystals are often striated lengthwise, and doubly terminated crystals are occasionally found. 

Tuesday, July 1, 2014

Mineral Specimen: ADAMITE (Zinc Arsenate Hydroxide)

Chemical Composition:   Zn2AsO4OH
Provenance: Durango, MEXICO

Adamite occurs as a secondary mineral in the oxidized zone of zinc- and arsenic-bearing hydrothermal mineral deposits. It occurs in association with smithsonite, hemimorphite, scorodite, olivenite, calcite, quartz and iron and manganese oxides.

The yellow to bright lime-green colored crystals and druze along with its distinctive fluorescence make adamite a favorite among mineral collectors. Found in Mapimí, Durango, Mexico; Greece; and California and Utah in the United States.

Adamite was named after the French mineralogist Gilbert-Joseph Adam (1795-1881). It was first described in 1866 for an occurrence at the type locality of Chañarcillo, Copiapó Province, Atacama Region, Chile.