SIMPLE MINERALS. 249 



SIMPLE MINERALS. 



BY E. HITCHCOCK, JE. 



In the description of the minerals of Vermont, the principal authorities used will be 

 Dana's System of Mineralogy, and Shepard's Treatise on Mineralogy, which are the most 

 complete works on American Minerals in this country extant. 



As these authors differ somewhat in their systems of classification, it may be well here, 

 for the convenience of those wishing to study the minerals of Vermont, to have both sys- 

 tems briefly explained before attempting specific descriptions. 



Prof. Dana considers all crystals as capable of being derived from thirteen shapes, 

 called primary forms. These are the cube, regular octahedron, rhombic dodecahedron, 

 right square prism, square octahedron, right rectangular prism, right rhombic prism, 

 rhombic octahedron, right rhomboidal prism, oblique rhombic prism, oblique rhomboidal 

 prism, the hexagonal prism, and the rhombohedron. These are grouped together under 

 six systems : 



1. Monometric, including the cube, regular octahedron, and rhombic dodecahedron. 



2. Dimetric, the right square prism, and the square octahedron. 



3. Trimetric, right rectangular prism, right rhombic prism, and rhombic octahedron. 



4. Monoclinic, right rhomboidal prism, and the oblique rhombic prism. 



5. Triclinic, the oblique rhomboidal prism. 



6. Hexagonal, including the hexagonal prism, and the rhombohedron. 



Prof. Shepard regards the primary forms of crystals as only eight in number. These 

 are, 1. The cube ; 2. The right square prism ; 3. The right rectangular prism ; 4. The 

 right rhombic prism ; 5. The right oblique angled prism ; 6. The oblique rhombic prism ; 

 7. The doubly oblique prism ; and 8. The rhomboid. 



In describing the minerals of Vermont, the plan adopted will be to give the primary 

 form so far as it is known, and other physical characteristics. In addition to this will be 

 given the chemical characters of the species, and a complete analysis of all Vermont 

 minerals so far as they have been made. The practical uses of each species, too, will be 

 added, so far as it is not the same as that mentioned under the head of Economic Geology, 

 in this Report. A catalogue of all the Vermont localities will* also be added to this part 

 of the Report. The minerals will be grouped together under the rocks in which they 

 occur. (D.) refers to Prof. Dana as authority, and (S.) refers to Prof. Shepard as authority. 



MINERALS IN THE TERTIARY SERIES. 



The minerals found in the Tertiary of Vermont are Pyrolusite, Psilomelane, Braunite, Brown Iron Ore, 

 Yellow Ochre, Mountain Leather, Calcite, Kaolin and Lignite. 



Pyrolusite. This is an important ore of manganese, known as the Anhydrous Binoxyd. Some varieties 

 of it contain a trace of Silica and Baryta. This primary form is a right rhombic prism, and is often found 

 columnar and granular. In color it is bluish-black, though often, as at Chittenden, it occurs in small 

 brilliant, steel-gray crystals. This is often found in connection with other ores of manganese. 



It is found in Vermont at Chittenden, Bennington, Brandon, Irasburgh and Monkton. 



In the State Cabinet it may be seen under the Nos. 79 to 90 inclusive. 

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