Answer: euclase

AnswerCrossword Clue
EUCLASECrystal mineral
EUCLASEGreenish gem
euclaserare green or blue mineral, beryllium aluminum silicate, BeAlSiO4(OH), occurring in prismatic crystals
euclasea mineral that consists of a brittle silicate of beryllium and aluminum in pale yellow, green, or blue prismatic crystals and is used especially as a gemstone