Corkscrew Cave, Arizona
Speleothems: Collaroids
Frequency: Extremely Rare
Other geologic settings: Hundreds of solution-collapse breccia pipes were identified in Northwest Arizona. The botton of thes pipes were dated in the Mississippian Redwall Limeston, the most karstified carbonate unit along the Grand Canyon.
Location within cave: Green Mineral Room
First description of cave occurrence: Onac, B.P., Hess, J.W., White, W.B., 2007. The Relationship between the Mineral Composition of speleothems and Mineralization of Breccia Pipes: Evidence from Corkscrew Cave, Arizona, USA. The Canadien Mineralogist 45: 1177-1188.
Water: None
Type of rock: MIssissipiian Redwall Limestone
Group: Oxides
Chemical formula: As2O3
[According to the official IMA-CNMNC List of Mineral Names (http://nrmima.nrm.se/imalist.htm)]
Deposition and stability: Lowering of the Colorado River triggered reorganization of the hydraulic gradient. This reorganization enhanced circulation through the epikarst to the water table. Redox elements were leached along the pipes allowing other insoluble minerals to be precipitated.
Diagnostic features: Octahedral crystals showing perfect cleavage after {010}
SEM
Mineral assemblage: Associated with Conichalcite and Pharmacolite
The octahedral crystals showing perfect cleavage after {010} and the As-O composition suggest the mineral is Arsenolite