Abstract

Paraspurrite is discredited as a mineral species. No type material was available necessitating collecting new material from the original locality. A crystallographic study shows paraspurrite to be polysynthetically twinned spurrite, twin law by reflection on {001}. The spurrite cell calculated from XRPD unit-cell refinement is a = 10.478(3), b = 6.700(2), c = 14.127(3) Å, β = 101.02(2)°, V = 972.8(3) Å3. The cell refined on two “twinned” crystals yielded: a = 10.494(1), b = 6.7116(6), c = 28.216(3) Å, α = 90.059(6), β = 100.132(5), γ = 90.023(6)°. This monoclinic primitive cell transforms to monoclinic B (Fig. 22): a = 10.494, b = 6.7116, c = 55.56 Å, α = 90, β = 90.6, γ = 90°, which corresponds to a sub-cell described as “paraspurrite” by Colville and Colville (1977); space group P21/a with cell parameters: a = 10.473, b = 6.706, c = 27.78 Å, α = 90, β = 90.58, γ = 90°. The discreditation has been approved by the IMA Commission on New Minerals, Nomenclature and Classification.

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