Symesite

symesite

mereheadite

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Formula: Pb₁₀(SO₄)O₇Cl₄.H₂O
Halide, nadorite group
Crystal System: Triclinic
Specific gravity: 7.3 measured, 7.23 calculated
Hardness: 4
Streak: White
Colour: Pink
Solubility:
Common impurities
Environments

Hydrothermal environments

Symesite is a very rare mineral known only from the type locality to date (November 2020).

Localities

At the type locality, Torr Works Quarry, Cranmore, Mendip, Somerset, England, UK, symesite occurs as a secondary low-temperature mineral formed from metalliferous brines moving along fractures in the oxidised zone of a manganese-lead-copper deposit in limestone. It occurs as crystal blebs up to 2 mm long and as crystalline aggregates up to 1 cm in diameter. Associated minerals include cerussite, hydrocerussite, paralaurionite, blixite, chloroxiphite, pyrolusite, coronadite, hematite, parkinsonite and mereheadite (AM 85.1526-1533, HOM). An example has been found with white symesite enclosing orange-brown mereheadite (JRS 13.25-26).

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