Gaildunningite
Gaildunningite is an IMA-recognized mineral species in the halide class, with the chemical formula Hg²⁺₃[NHg²⁺₂]₁₈(Cl,I)₂₄.
It crystallizes in the orthorhombic crystal system (space group Amam).
Key properties: Mohs hardness 3; specific gravity 8.22; Orange streak; Vitreous to adamantine luster.
IMA symbol Gai, IMA status: approved, named in 2018.
Found in a tectonically emplaced section of oceanic crust, the metamorphism of which released Hg-bearing fluids that migrated along fractures within silicified serpentinite and produced the mercury mineralization.
It is found associated with Quartz, an undescribed (Hg-N)-bearing mineral (CCUK-18).
The mineral was named to honor Gail E. Dunning (b. 1937), a prominent field-collector from the New Idria mining district who has discovered many new mercury-bearing minerals.