154 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



eral term of micas has been the object of some profound in- 

 vestigations by Kokscharof and Tschermak. Hitherto it has 

 been customary to regard part of the micas as hexagonal 

 (e. <7.,biotite) and others as orthorhombic (e. </., muscovite). 

 The conclusion reached by Kokscharof, after the examination 

 of many specimens of the different species, and a very long 

 series of measurements, is that " the species are all monoclinic 

 with an anode of 90 0' 0"." Tschermak concludes also that 

 all the species belong to the monoclinic system, and assigns 

 to them an angle of obliquity differing by "a minute only 

 from 90. The latter mineralogist has also investigated 

 with great care and minuteness the optical properties of the 

 different species, and finds in them conclusive evidence of the 

 monoclinic character of the crystals. He divides the species 

 into two groups, according as the plane of the optic axis is 

 (1) perpendicular, or (2) parallel, to the plane of symmetry. 

 The first class includes the species muscovite, lepidolite, pa- 

 ragonite, and margarite, and a portion of the biotites to 

 which he gives the name anomite. The second class includes 

 phlogopite, lepidomelane, zinnwaldite, and the larger part of 

 the magnesia-micas, or biotite, to which he gives Breithaupt's 

 old name, meroxene. The second part of Tschermak's paper, 

 including the discussion of the chemical composition of the 

 species, has yet to appear, and will be looked for with interest. 



Dr. Scharff, of Frankfort, has. published another of his val- 

 uable crystallogenic memoirs upon calcite. He discusses 

 the interior relation between the different crystalline forms 

 of the species, and deduces from them some conclusions in 

 regard to the genetic origin of the crystals. 



Of other important memoirs may be mentioned that of 

 Schrauf upon the crystallography of brookite and of lanar- 

 kite ; by Vom Rath, upon the crystalline form of gold, upon 

 rutile, etc.; of St diver, upon the minerals of Latium. 



AMERICAN RESEARCHES. 



A considerable number of new minerals, described by 

 American mineralogists, are included in the following list. 

 In addition to them, many other papers of more or less im- 

 portance have been published. 



The rare minerals of the tantalite and columbite group, 

 spoken of in a former issue of the Record as having been 



