New Mexico Geological Society Annual Spring Meeting — Abstracts

In and near the Black Range, New Mexico, Tertiary rhyolite tuffs and flows host several I kaolin deposits. The largest-200 million tons reserve-and most extensive of these deposits is the Kline Mountain kaolin deposit which occurs as a result of advanced argillic alteration.

The mineral assemblage of the deposit, which was studied, contains kaolinite, alunite, I trldymite, and quartz. XRD data indicate that there are mineralogical differences in clay-size particles between the core samples and the surface samples. On the basis of the XRD data the kaolinite near the surface is well-crystallized and different from that of the cores. Most of the kaolinite, which is characteristic of an in situ alteration, is probably authigenic. The enrichment of alunite in cores might be related to vertical and horizontal changes in leaching. According to the XRD data, the common silica mineral in the deposit is trldymite. The deposit is a result of kaolinization, alunitization, and silicification that appear to have come from two periods of Tertiary alteration and mineralization, both of which have affected the Kline Mountain rhyolite and the Taylor Creek rhyolite porphyries.

Particle-size analysis shows that the well-crystallized kaolinite without any impurities represents the highest percentage of clay-size material. However, the kaolinite, which includes alunite and silica, has relatively coarse size particles. The core samples display coarser material than the outcrop samples.

To date, the Kline Mountain deposit appears to contain sizeable quantities of good quality kaolinite which has acceptable physical and chemical properties for use by industry. The kaolin deposit is currently not in production; however, it has been exploited primarily for paper and ceramic tile as a coating, and the oil industry as a filler and absorbent material. The production has been by open pit mining methods. Although kaolinite is the chief mineral in the deposit, much of it contains excessive amounts of alunite and silica (trldymite?) which makes it of dubious commercial value.

Although the kaolin in the Kline Mountain deposit has been used in several branches of industry in the past, suitable rock units and appropriate hydrothermal alteration in the area make the deposit attractive for continued evaluation in order to find new application(s) for industry. Consequently, it is suggested that further study be done to determine if this clay deposit would be suitable for continued industrial use.