250 SIMPLE MINERALS. 



Psilomelane. This is another common ore of manganese, a hydratcd oxyd, which occurs not in crystals, 

 but in mammillary masses, of an iron-black color, passing into steel-gray, with submetallic luster. 



This at Bennington, Chittenden, and Brandon is found in connection with Pyrolusite. 



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



It may be seen in the Cabinet in connection with nearly all the other specimens of manganese. 



Braunite. This is another of the oxyds of manganese, though not of so frequent occurrence as the two 

 last described. It belongs, in crystalline form, to the Dimetric system of Dana. It is brittle, with a sub- 

 metallic luster, and of a dark brownish black color. 



It is found in Vermont at Brandon, Chittenden, and Pittsford ? Wallingford? Bristol? 



Brown Iron Ore, or Limonite of Dana. This is the hydrous Peroxyd of Iron, and occurs usually in 

 reniform, stalactitic, or botryoidal masses, with a fibrous structure. Sometimes it is massive, and some- 

 times earthy, but is never crystallized. In color it is brown with its various shades; sometimes nearly black 

 Brown iron ore is one of the most important ores of iron, making that metal which is readily convertible 

 into steel, especially if the ore is reduced by charcoal. 



It is found in Vermont at Bennington, Monkton, Pittsford, Putney, Eipton, Sherburne, Chittenden 

 Dorset, Manchester, Stamford, Swanton, Bristol, Huntington, Starksboro, Highgate, Warren, Colches- 

 ter, Milton, St. George, Brandon, E. Bennington, E. Shaftsbury, S. Wallingford, Plymouth. 



Specimens of brown iron ore may be seen in the Cabinet from Nos. 102 to 112 inclusive. 



Yellow Ochre. This is an earthy ore of iron probably of the same composition as limonite and hematite. 

 It is of a yellow color and often of a consistency of chalk. It is obtained abundantly at all the localities 

 where limonite is found in Vermont, and is easily obtained by washing and subsequent deposit. At Bran- 

 don and Bennington it is procured in immense quantities. 



Specimens of yellow ochre are to be seen in the Cabinet under Nos. 124 and 125. 



Red ochre is not found in nature, but is simply the yellow treated to heat. In this case the iron is 

 carried to another stage of oxydation. 



Mountain Leather. This is a fanciful name given to one of the kinds of asbestos, which is itself a variety 

 of hornblende. It occurs in thin paper-like masses, lying between different portions of a rock, and the 

 fibers are so small and closely interlaced that the whole has an appearance more like leather than like an 

 interlacement of fibers. Another name given to essentially the same thing is mountain or rock cork, since 

 masses of it are of so slight a specific gravity that they will float on the water. 



This mineral has been found in Swanton, and is No. 220 in the State Collection of Minerals. 



Kaolin or Porcelain Clay. This should hardly be regarded as a simple mineral, since it exists in conse- 

 quence of the decomposition of simple minerals the feldspars. Prof. Dana says : "When the infiltrat- 

 ing waters contain traces of carbonic acid, the feldspar acted on first looses its lime, if a lime feldspar, 

 by a combination of the lime with this acid ; next its alkalies are carried off as carbonates, if the supply of 

 carbonic acid continues, or otherwise as silicates in solution. The change thus going on ends in forming kaolin 

 or some other hydrous silicate. The carbonate of soda or potash or the silicates of these bases, set free, may 

 go to the formation of other minerals the production of pseudomorphic or metamorphic changes and the 

 supplying fresh and marine waters with their saline ingredients." It is not easy always to distinguish this 

 from the following variety. 



Pipe Clay is found in several places in Vermont, among which may be mentioned Plymouth, Benning- 

 ton, Pownal, Brandon and Monkton. It is found of different qualities and colors, as will be described 

 under Economic Geology. 



Closely in connection with the kaolin of the tertiary series, should be mentioned the lignite or brown coal. 

 It occurs abundantly at Brandon where it was used as fuel for the steam engine at the shaft. With it are 

 also found fruits, evidently belonging to the wood now converted into lignite. No similar fruits have as yet 

 been discovered on this continent elsewhere than at Brandon, though they occur in the Isle of Sheppey, 

 England, and in the brown coal of Germany. These, however, have been already described. 



No 10 in the cabinet is a specimen of lignite from Brandon. 



