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Formula: Pb4ZnZn2(PO4)4(OH)2
Phosphate, dongchuanite group
Crystal System: Triclinic
Specific gravity: 6.06 calculated
Hardness: 2 to 2½
Streak: Colourless
Colour: Turquoise–greenish blue; pale blue to light blue in transmitted light
Luminescence: No fluorescence under UV
Solubility: Easily dissolves in dilute hydrochloric acid
Environments
Sedimentary environments
Hydrothermal environments
Dongchuanite is a new mineral, approved in 2021 and to date (August 2023) reported only from the type locality.
Localities
At the type locality, Sanguozhuang, Dongchuan District, Kunming, Yunnan, China, it is generally believed that the ore
deposit was formed by sedimentation–hydrothermal transformation. There is a wide variety of mineral species in the
deposits, with more than 20 species of polymetallic sulphide minerals and more than 30
supergene minerals identified so far.
Dongchuanite was found in an abandoned mine shaft, occurring on a
sandstone fracture around
copper-sulphide ore veins, that are clearly of
supergene origin. The dongchuanite may have been formed
by the weathering of copper, lead and
zinc sulphides under the action of surface water. Associated minerals are
quartz, theisite,
veszelyite, kipushite,
tangdanite, tyrolite,
arsenoveszelyite,
bayldonite,
cuprodongchuanite and
hemimorphite.
Dongchuanite is composed of spherical aggregates of microscopic lamellar crystals. The size of the spherical
aggregates ranges from 0.5 to 1 mm, and the thickness of single lamellar crystals ranges from 5 to 20 μm
(MM 87, 611–618).
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