This article was published in the November issue of Wayne County Gem and Mineral Club News. Ninety-one dravites from the WCGMC collection were used to wish the members Happy Halloween.
Dravite is a tourmaline within the Alkali Subgroup 1. This means that the X-site in the complex formula below is predominantly occupied by sodium (Na). In the case of dravite the Y site is occupied by magnesium (Mg) and the Z site is aluminum (Al). The boron cyclosilicate mineral is always dark in color, ranging from chocolate brown to almost jet black. Occasionally, there is sufficient chromium in the Y and/or Z site to impart a dark green color. Dravite is most commonly found in metamorphosed limestones and in higher grade mafic schists.