acleistous

mollusque commented on the word acleistous

A little used term in crystallography, literally meaning "unclosed", hence "open".

"The forms are all open forms, and the class may be called the acleistous ditrigonal or the polar ditrigonal class: they were regarded as hemihedral with inclined faces."

--W. J. Lewis, 1899, A Treatise on Crystallography

January 6, 2008