Brianyoungite

minerals

hydrozincite

ktenasite

sphalerite

Formula: Zn3(CO3)(OH)4
Compound carbonate
Specific gravity: 3.93 to 4.09
Hardness: 2 to 2½
Streak: White
Colour: White, colourless
Solubility: Readily soluble in 1:10 acids (Dana)
Environments

Hydrothermal environments

Brianyoungite is a secondary post-mining mineral in limestone-hosted oxidised lead-zinc ores (Webmin).

Localities

At the type locality, the Brownley Hill mine, Alston Moor, Eden, Cumbria, England, UK, rosettes of brianyoungite are associated with gypsum on rubbly limestone, or black shaly coatings on limestone, within the oxidised zone. Apart from oxidising pyrite with accompanying goethite and iron staining, the only other minerals noted are ktenasite and smithsonite. Brianyoungite developed as individual rosettes on the surface of specimens or within cavities, and as coalescences forming thin surface layers. Additionally, it may be encapsulated by gypsum (MM 57.665-670, AM 79.1009). It is almost certainly formed by post-mining oxidation (Minrec 31.3.244).

At the Tynebottom mine, Alston Moor, Eden, Cumbria, England, UK, Small crusts of minute crystals of brianyoungite have been found in the carbonate field of four specimens, mostly in intimate association with crusts of hydrozincite. On three of the specimens, gypsum was in close association (JRS 10.3-8).

At the Elgar Mine, Bontgoch, Ceredigion, Wales, UK, brianyoungite is extremely rare, but has been found as as minute rosettes to 0.3 mm of crystals coating a single specimen of iron-stained quartz and galena from the deep adit dumps (MW).

At Frongoch Mine, Devil's Bridge, Ceredigion, Wales, UK, spherulitic aggregates of crystals of brianyoungite up to 0.5 mm across have been found in a galena-rich matrix (MW).

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