SHERL, BURGERITE
Characteristics of the mineral.
Sherl is a black variety of tourmaline. The most widely distributed black tourmalines in nature are called schurls. Obtained for decorative purposes (not a jewelry version of tourmaline). The diagnostic feature is the triangular shape of the cross-section or the cleavage of crystals characteristic of tourmaline. Can occur as black sticks-inclusions in quartz-hairy (quite common inclusion).
Burgerite - brown, black with brown-red iris, tourmaline is not of jewelry quality. Unlike absolutely opaque sherla, it can shine through or be partially transparent in bright light.
Schorl. Sahatani dol., Madagascar (without breed). On right. The Sherbles. Korets, Ukraine. Photo: © А.А. Evseev.
Poisonous and radioactive dangerous stones and minerals
** - poisonous stones and minerals (mandatory check in the chemical laboratory + explicit indication of toxicity).
** - radioactive stones and minerals (mandatory check on the standard dosimeter + ban on open sales in the case of radioactivity over 24 milli / g / h + additional measures of population protection).
All rare stones are subject to mandatory inspection at the standard dosimeter for the permissible level of radiation and in the chemical laboratory for the absence of poisonous and evaporating components that are dangerous to humans and the environment.
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