Webster's Revised Unabridged Dictionary
Gr. e'y^ well, easily + to break. Cf. F. euclase, G. euklas,. See named from its brittleness
Chambers's Twentieth Century Dictionary
Fr.,—Gr. eu, well, klasis, breaking.
Euclase occurs with topaz at Boa Vista, near Ouro Preto (Villa Rica) in the province of Minas Geraes, Brazil.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 8" by Various