E. MINERALOGY AND GEOLOGY. 133 



tallizes in the hexagonal system, and has a specific gravity 

 of 2.6. Professor Rath, however, not long since detected a 

 second species of silica, which he called Tridyraite, having a 

 specific gravity of only 2.3, crystallizing in the hexagonal 

 system, but with different parameters from those of quartz. 

 The discovery of Professor Maskelyne shows that silica is 

 trimorphous, and for this third species he proposes the name 

 of Asmanite. The specific gravity is very low, 2.245, in 

 this resembling Tridymite, from which, however, it differs 

 in being a biaxial mineral, and belonging to the orthorhom- 

 bic or prismatic system. Its hardness is 5.5. Two analyses 

 show that it consists essentially of silica, and contains but 

 a small percentage of foreign matter. The Asmanite is as- 

 sociated in the Breitenbach meteorite with enstatite, chro- 

 mite, triolite or meteoric pyrites, and nickeliferous iron. 

 10 A, July, 1872,389. 



IRON SAND ON THE PACIFIC COAST. 



The discovery that the iron sand, so abundant on the shores 

 of Australia and New Zealand, is capable of being smelted by 

 a very simple and cheap process into iron of the best quali- 

 ty has stimulated search for similar deposits on the western 

 coast of the United States ; and at a meeting of the Academy 

 of Sciences of San Francisco,Dr. Stout announced that he had 

 found such a deposit within fifty miles of that city, and in- 

 dulged in glowing anticipations of an important addition to 

 the resources of the state, more valuable, perhaps, than her 

 treasures of gold or quicksilver. 



Similar iron sands are found at various points on the west- 

 ern coast, and are extremely abundant throughout the whole 

 chain of the Aleutian Islands. It is, perhaps, from the vol- 

 canic character of the region, that Dr. Stout announced the 

 novel hypothesis that this iron was probably formed by the 

 discharge from volcanoes of vapor containing iron in suspen- 

 sion, and which, becoming condensed by electric action, fell 

 again on the earth or into the water as iron sand, this being 

 subsequently washed up and accumulated on the shores. 



Dr. Gibbons did not feel inclined to accept this theory, and 

 believed that it was produced by the wearing away by the 

 action of the sea of the sea-side strata containing iron, com- 

 minuting it into fine powder. lie anticipated one difficulty in 



