1910–1911
Britannica 11th
Encyclopaedia Britannica · 11th edition
EUCLASE, a very rare mineral, occasionally cut as a gem-stone for the cabinet. It bears some relation to beryl in that it is a silicate containing beryllium and aluminium, but hydrogen is also present, and the analyses of euclase lead to the formula HBeAlSiOs or Be(A10H)SiO4. It crystallizes in the monoclinic system, the crystals being generally of prismatic habit, striated vertically, and terminated by acute pyramids. Cleavage is perfect, parallel to the clinopinacoid, and this suggested to R. J. Haiiy the name eu…
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- Vol. 9, pp. 878-878