Elements of mineralogy, crystallography and blowpipe analysis from a practical standpoint .. . ^W. Urals. Haddam, Conn. Crystallization.—Orthorhombic a : b : c = : i : flat plates or flat contact twins with feather-like striations,Fig- 555- Alexandrite occurs in simple, Fig. 554, or twinned crys-tals showing unit pyramid / and prism in with brachy pyramid r^ 2& : b : 2c and prism n = 2 d : 00 c. Angles are m m =129° 39; tin=gi° 32; pp= 139° 53; rr= 107° 43. Optically -(-. Axial plane the brachy pinacoid. Acute bisec-trix vertical. Pleochroic. Physical Characters. H.,

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Elements of mineralogy, crystallography and blowpipe analysis from a practical standpoint .. . ^W. Urals. Haddam, Conn. Crystallization.—Orthorhombic a : b : c = : i : flat plates or flat contact twins with feather-like striations,Fig- 555- Alexandrite occurs in simple, Fig. 554, or twinned crys-tals showing unit pyramid / and prism in with brachy pyramid r^ 2& : b : 2c and prism n = 2 d : 00 c. Angles are m m =129° 39; tin=gi° 32; pp= 139° 53; rr= 107° 43. Optically -(-. Axial plane the brachy pinacoid. Acute bisec-trix vertical. Pleochroic. Physical Characters. H., Sp. gr., to Lustre, vitreous to greasy. Translucent to transparent. Streak, white. Tenacity, brittle. Color, pale yellowish green to emerald green. Before Blowpipe, Etc.—Infusible. In powder, is turned blueby cobalt solution. Insoluble in acids. Varieties.—Alexandrite, the deep emerald-green variety, whichis columbine red by transmitted light. Cymophane or Cats Eye.—Yellowish-green and —No fine gems have been found in the United States, although

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