Arrangement of Minerals^ 361 



Genus XIII. Almandine-Spar. 

 Rhombohedral. Colour red. Hardness = 5.0 — 5.5. Sp. gr. 

 = 2.84^2.89. 



1. Rhombohedral Almandine-Spar, or Eudyalite. 

 Genus XIV. Azure-Spar. 

 Prismatic. Amorphous. Cleavage imperfect. Colour blue — 

 green. Hardness = 5.0 — 6.0. Sp. gr. = 2.75 — 3.1. 



1. Prismatic Azure-Spar or Lazulite. 2. Prisraatoidal Azure -Spar, 

 or Blue-Spar. 3. Uncleavable Azure-Spar, or Calaite {Tur- 

 quoii). 



Genus XV. Adiaphane Spar.* 

 Pyramidal. Prismatic. Amorphous. Cleavage imperfect — 

 uncleavable. Hardness = 5.5 — 7.0. Sp. gr. = 2.9 — 3.4. 



1. Pyramidal Adiaphane Spar, or Gehlenite. 2. Prismatic Adiaphane 

 Spar, or Saussurite. 3. Uncleavable Adiaphane Spar, or Ne- 

 phrite. 



Order V. GEM. 

 Not metallic. No metallic adamantine lustre. Streak 

 white. Hardness = 5.5 — 10.0. Sp. gr. = 1.9 — 4 7. 

 Genus I. Andalusite. 

 Prismatic. Cleavage perfect in two somewhat oblique directions, 

 parallel to the axis. Hardness = 7.5. Sp. gr. = 3.0 — 3.2. 

 1. Prismatic Andalusite (^Feldspath apyre, HaUy). 

 Genus II. Corundum. 

 Tessular. Rhombohedral. Prismatic. Hardness = 8.0 — 9.0. 

 Sp. gr. = 3.5 — 4.3. 



1. Dodecahedral Corundum, or Spinel Ruby. (Alumine MagnesUe 

 ou Spinelle, H.) 2. Octahedral Corundum, or Automalite {Spi- 

 nelle Zincifere, H.) 8. Rhombohedral Corundum, or Oriental 

 Ruby and Sapphire {Common Corundum, Adamantine- Spar, and 

 Emery'), 4. Prismatic Corundum, or Chrysoberyl {Cymophane, 

 H.) 



Genus III. Diamond. 

 Tessular. Hardness •= 10.0. Sp. gr. = 3.4 — 3.6. 

 1. Octahedral Diamond. 



Genus IV. Topaz. 

 Prismatic. Cleavage axotomous. Hardness = 8.0. Sp. gr. = 

 3.4 — 3.6. 



1. Prismatic Topaz {Alumine FhiaU Siliceuae, ou Topazc, H. Phy- 

 salit, Picnit), 



t Adiaphane-spar, so named on account of the low translucency of its 

 varieties. 



