Hemimorphite, Zn4Si2O7(OH)2·H2O, is named for the crystallographic phenomenon it exemplifies. A hemimorphic crystal is one whose opposite faces are symmetrically inequivalent.
Aragonite is a crystalline form of CaCO3, calcium carbonate.
Mexican “Trancas” geodes are surface mined about 220 miles south of El Paso, Texas in Chihuahua province, Mexico. These particular geodes, while not as colorful as the “coconut” geodes, do contain primarily clear or drusy quartz linings and may also have calcite, fluorite, and quartz scepters as well. One of the most notable features of these geodes is their fluorescent ability due to trace uranium content (not enough to harm life). Under shortwave UV light, approximately 80-85% of these geodes fluoresce bright green.
with feldspar orthoclase