214 THE MINERALS OF TASMANIA. 



SYSTEMS OF CRYSTAL FORMS. 



No. I. Isometric — also known as the Cubic, Tesseral, Begular, 

 and Monometric. 



All forms having three equal axes at right angles 

 to each other are referred to this system. 



Be presented by: Galena, sphalerite, garnet, 

 diamond, fluorite, tetrahedrite, spinel, pyrite, mag- 

 netite, and cuprite. 



No. II. Tetragonal — also known as the Pyramidal and 

 D'lmetric. 



Includes all forms which have three rectangular 

 axes, of which the two lateral are equal, and the 

 vertical one either shorter or longer. 



Bepresented by: Cassiterite, zircon, idocrase, 

 rutile, scheelite, and chalcopyrite. 



No. III. Hexagonal — also' known as the Bhombohedral. 



Includes all forms having four axes, three equal 

 lateral axes in a common plane intersecting at 

 angles of G0°, and a vertical axis at right angles. 



Bepresented by: Quartz, beryl, apatite^ calcite, 



Syromorphite, siderite, hematite, tourmaline, and 

 olomite. 



No. IV. Orthorhombic — also known as the Trimetric, Fris- 

 matic, and Orthotype. 



Includes all forms which have three unequal axes 

 at right angles to each other. 



Bepresented by: Baryte, stibnite, arsenopyrite, 

 anglesite, topaz, and cerussite. 



No. V. MoNOCLiNic — also known as the Oblique and Hemi- 

 orthotype. 



Includes all forms having three unequal axes 

 with one of the axial inclinations oblique. 



Bepresented by: Gypsum, orthoclase, augite, 

 hornblende, muscovite, and crocoisite. 



No. VI. TRicLiNic^^also known as the Anorthic, Double 

 Oblique, and Anorthotype. 



Includes all forms which have three unequal axes, 

 with all their intersections oblique. 



Bepresented by: Axinite, labradorite, cyanite, 

 rhodonite, albite, and anorthite. 



