Clinoptilolite west of Cuchillo Negro Creek, New Mexico--Zeolite authigenesis of the tuff of Little Mineral Creek
— Mark R. Bowie and James M. Barker

The Tertiary tuff of Little Mineral Creek crops out in the southern end of the Winston graben about 6.5 km south of Winston, Sierra County. The unit consists of thin to massive, partly silty to sandy, zeolitic tuff interbedded with mudstone, siltstone, and conglomerate. The tuff contains approximately 50% clinoptilolite. The clinoptilolite formed as a diagenetic-alteration product most likely via reaction of alkaline/saline meteoric and/or low-temperature hydrothermal fluids with vitric tuff in an open hydrologic system.