This piece was a present from my geologically minded children, it guards my heirloom irises
and for your edification...
" The calcite crystals, unlike most of the other mineral decorations, were presumably formed under water; that is, at a time when the cave was filled with solutions. Similar crystals have been "grown" in laboratories, where it was found that by adding certain impurities in varying amounts, the form of the crystal could be changed. In fact over 300 different crystal forms of calcite are known."
|Typical occurrence of calcite crystals (mostly Dogtooth Spar). The best specimens are found in vugs or cavities and on the underside of protruding ledges. Typical Calcite Crystal Forms, normally only the upper half of the crystal will be seen. (bottom, center).|
information from Jewel Cave NP