Note 95 — Chapter IV · The Microscopic and Optical Characters of Minerals.
Reading edition
The distinction between zoisite α and β (essentially orthorhombic, but may be composite triclinic twins) and clinozoisite (monoclinic close to orthorhombic) depends on differences in position of plane of optic axes; axial figures shown by cleavage plates; dispersion; anomalous interference colors; etc. See Weinschenk’s Die Gesteinbildenden Mineralien, p. 83. 1901.