New Mexico Mineral Symposium — Abstracts

Kartchner Caverns, located just south of Benson, Arizona, contains a diverse and significant mineralogy. It is diverse in that six chemical classes are represented by the cave mineralogy: carbonates, nitrates, oxides, phosphates, silicates, and sulfates. It is significant for a number of reasons:

• world's longest soda straw
• largest and most massive column in Arizona
• first reported occurrence of nontronite and rectorite as cave minerals first cave occurrence of "birdsnest" needle quartz
• first modern description of nitrocalcite and its rare occurrence as a cave mineral one of the most extensive occurrences of brushite moonmilk in the world
• first reported occurrence of "turnip" shields

The diverse and interesting mineralogy of Kartchner is due to an unusual set of circumstances. Unlike most limestone caves, Kartchner Caverns is located near igneous terrain. Alaskite granite borders the Escabrosa Limestone along fault zones to the west, and the Pinal Schist underlies the cave. The dry Arizona desert supplies another condition: the low relative humidity causes the efflorescence of nitrocalcite in the entrance zone of the cave. Bats add the third ingredient, bringing phosphates and nitrates into the cave. In setting and mineralogy, Kartchner Caverns most nearly resembles the caves of the Transvaal, South Africa, where a hot and dry climate combined with an igneous rock/bat guano source of cations and anions has produced an unusual cave environment in which a number of minerals can form.