Geology and alteration of the Kline Mountain kaolin deposit, Sierra County, New Mexico
— Iskender Isik, Kenneth F. Clark, and George S. Austin

The kaolinized tuff of the Kline Mountain area lies on the eastern margin of the Mogollon-Datil volcano-tectonic province, a major mid-Tertiary volcanic center. On the eastern margin of this center is the extensional environment of the Rio Grande rift. Faults in the study area display dominant northwest and northeast trends. The stratigraphy in the Kline Mountain clay deposit area consists of mid-Tertiary bimodal volcanic and volcaniclastic deposits. The kaolin deposit occurs within the advanced argillic zone of the tuff of Kline Mountain as a result of hydrothermal alteration. The deposit is a result of kaolinization, alunitization and silicification that is related to mid-Tertiary hydrothermal activity associated with a rhyolite porphyry intrusion. On the basis of calculated mineral compositions from chemical analyses and XRD data, there is an inverse relationship between kaolinite percentage and proximity to the intrusion. Conversely, there is a proportional relationship between alunite content and proximity to the intrusion. XRD data indicate that kaolinite is a principal mineralogical constituent in the deposit whereas smectite was identified locally. The other major constituent is fine-grained silica (cristobalite and/or tridymite?). Small amounts of opaque oxides, and hematite-cassiterite mineralization associated with fractures, have also been identified. That part of the deposit that was investigated in detail contains over 3 million tons of clay and the whole deposit is reported to contain over 200 million tons. In spite of high standard brightness of 94%, the silica content is considered to be a drawback for use in the paper industry. In 1969, 900 tons of the deposit were sold as an oil absorbent. Recently, experiments have shown the suitability of the deposit in the manufacture of white brick.