Shannonite
Shannonite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Pb₂O(CO₃).
It crystallizes in the orthorhombic crystal system (space group P2_12_12_1).
Key properties: Mohs hardness 3–3.5; White streak; Waxy luster.
IMA symbol Snn, IMA status: approved, named in 1993.
A rare secondary mineral formed in the oxidation zone, probably by acidic groundwater reacting with cerussite, in a lead ore deposit (Grand Reef mine, Arizona, USA).
It is found associated with Cerussite, litharge, massicot, minium, hydrocerussite, fluorite, plumbojarosite, hematite, manganese oxides, quartz, muscovite (Grand Reef mine, Arizona, USA).
The mineral was named to honor David Michael Shannon (1942–2003?2002??ck??), mineral dealer and collector, Mesa, Arizona, USA, who provided the original material.