534 THE GEOLOGY OP MINNESOTA. 



[Greenstone. Diabase. 



Aye. Keewatin. 



Remark. In connection with Nos. 760-765 compare Nos. 1386-1395 which were 

 collected between the southwest corner of Ogishke Muncie lake and the summit of 

 East Twin peak; also Nos. 1756-1764 which were collected on a trip from Kekequabic 

 lake to the summit of West Twin peak. u. s. G. 



No. 761. "GREENSTONE." 



See under No. 760. 



Kef. Annual Report, x, page 97; Bulletin ii, page 121. 



M'ry. A compact, fine-grained, greenish rock, showing considerable pyrite. 



Mir. M. E. Wadsworth's description of this rock is as follows:* 



"The sections show an entirely altered rock, composed of greenish rlidrifr 

 scales, colorless miruceotix plates, and numerous granules of pi/ rite and may net Hr. 

 Although no absolute proof can be obtained from these sections to show the original 

 status of the rock, yet from what the writer has seen from other localities, lie 

 considers this to be a highly altered diabase, now forming a chloritic rock or compact 

 chlorite schist." 



Two sections examined. 



Aye. Keewatin. r. s. G. 



No. 762. DIABASK. 



See under No. 760. 



Ref. Annual Report, x, page 97. 



Mry. A fine-grained, black diabase. 



Afic. The section shows rather fresh, lath-shaped plagioclases in a dark back- 

 ground, composed of auyite, magnetite, alteration products of <tuyih>, and possibly some 

 unindividualized base. 



One section examined. 



Aye. Probably Cabotian or Mauitou. u. s. G. 



No. 763. DIABASK. 



See under No. 760. 



Ref. Annual Report, x, page 97. 



Meg. A fine-grained, compact, dark greenish rock. 



Mic. The section shows small, altered, much elongated, lath-shaped i>l<nji<>rl<ixi'x 

 in an altered, fine-grained background, which is composed essentially of fibrous 

 hornblende, chlorite scales and magnetite. 



One section examined. 



Aye. Keewatin. u. S- G . 



Bulletin ii, p. 121. 



