54 Geology and Mineralogy of a part of Massachusetts, &c. 
probably with oxide of iron. Also in Middlefield and 
Chester; Emmons. It is a fine powder, and not very 
abundant in the rock; enough however to cover it with 
flame when thrown on the fire. ‘The mica in this rock is a 
very bright green, and has sometimes been considered as 
oxide of chrome. 
Pulverulent sulphur is found also in Tyringham, in mi- 
ca slate, and in Wilmington, Vt. 
Also in Cummington, in the singular mineral discovered 
by Dr. Porter. 
3. PETROLEUM, 
Rises in small quantity on the surface of rather stagnant 
waters, in many places. 
4. GRAPHITE. 
Foliated and granular with augite at Hinsdale. Some- 
times it is nearly slaty, and in considerable quantity. Also 
in New Marlborough. 
The foliated variety is often found along the eastern part 
of this section, diffused through augite, granite, and va- 
rious minerals. It is often called sulphuret of molybdena, as 
graphite is not supposed to be so distinctly foliated. 
Most of it, however, is certainly graphite. Also in Cum- 
mington. 
5. PEAT. 
A bed of vegetable matter, approaching this substance, 
under the bed of marl in Pittsfield. In Canaan, N. Y. 
Barnes. 
CLASS IV. 
1. SULPHURKET OF IRON: 
Too common to mention localities,—associated with 
most rocks and minerals. In Chatham, N. Y. in flattened 
