DELHI QUARTZITE SERIES. 107 



The occurrence of actinolite rock, hornblende asbestos and talc 



0. Merrills views. in these localities seems to present some analo- 

 gies with that described by G. Merrill. 1 This 

 author states that at Alberton, Maryland the fibrous anthophyllite 

 occurs along the slickensided zone between a schistose actinolite 

 rock and a more massive serpentinous or talcose rock which 

 is also presumably an eruptive peridotite or pyroxenite. The 

 fibration, it is also stated, runs parallel with the direction of 

 movement as indicated. 



However, there are other views ; Heinrich Ries in Economic 

 other views. Geology (1910), in describing the Virginia 



deposits, which occur in beds of 30 to 165 feet 

 thick, in much the same terms as regards the colour qualities and 

 hardness as are applicable to the Idar rock, is of the opinion that 

 steatite in some cases has no doubt been derived from an altered 

 eruptive rock, but in others probably from magnesian sediments, 

 by metamorphism. In the New York deposits there are schistose 

 layers from a few feet to 50 feet thick in Pre-Cambrian gneisses 

 with belts of crystalline limestone. The schistose layers contain 

 tremolite and enstatite as the chief constituents and it is considered 

 that it is their alteration that has produced the talc by means of 

 water charged with carbonic acid. An interesting occurrence is 

 described from New Jersey, where talc occurs with serpentine in 

 dolomite, and near pegmatitic intrusions. The latter, by contact 

 metamorphism, developed tremolite, white pyroxene and phlogo- 

 pite in the limestone. Later, during break-thrust faulting accom- 

 panying minor folding, squeezing and faulting in this area, the 

 magnesian silicates were altered by water to talc and other pro- 

 ducts. 



These quotations seem to show that the particular way in which 

 steatite beds may be formed are many and various. 



The fourth occurrence of magnesian rocks, with their accessorv 

 (4) s. w. of Tlu.ravas. minerals > stretches south-west of Thuravas 

 for about l\ miles to a point in the Hathmati 

 river due east of Fatepur. It is a rather narrow band, probably 

 nowhere more than 300 feet thick, though lack of clean-cut sections 

 prevents any more accurate estimate. The outcrop rises and sinks 

 gently over the lower ends of the hill-spurs and is easily noticeable 



* " The non-metallic Minerals," 1st Edn. p. 183, New York. Wilev and Sons, Chapman 

 Hall and Co. • " 



