Carbuncle (gemstone) Carbuncle (gemstone) A carbuncle is any red gemstone, most often a red garnet. The word occurs in four places in many English translations of the Bible. The English King James translation is a rendering of the Hebrew Masoretic text (Old Testament) and Greek Textus Receptus (New Testament). "Carbunculus" is a word used in Latin for a small coal (or charcoal), and also for any of a number of precious or semi-precious stones, especially those of a red color.; Jerome apparently chose the term because of its similarity in meaning to the Septuagint's ἄνθραξ ("anthrax" meaning "coal"), which was in turn
Garnet rocks in which they grew. Garnet grains that lack compositional zonation commonly are interpreted as having been homogenized by diffusion, and the inferred homogenization also has implications for the temperature-time history of the host rock. Garnets are also useful in defining metamorphic facies of rocks. For instance, eclogite can be defined as a rock of basalt composition, but mainly consisting of garnet and omphacite. Pyrope-rich garnet is restricted to relatively high-pressure metamorphic rocks, such as those in the lower crust and in the Earth's mantle. Peridotite may contain plagioclase, or aluminium-rich spinel, or pyrope-rich garnet, and the presence of each