226 ALBERT JOSANNSEN 



amphibole-peridotite. Mica-peridotite was named by Diller^ 

 from an occurrence in Kentucky. In the type rock the olivine and 

 its alteration products form over 80 per cent, the ores, magnetite, 

 and ilmenite together 4.2 per cent, while biotite, garnet, etc., are 

 accessory. The rock number is (412). 



Amphibole-peridotite was first described as amphibole-gabbro 

 by Howitt.^ Later Rosenbusch^ compared the same rock with the 

 Schreisheim dike, and still later Verbeek"* called it amphibole- 

 peridotite. Hornblende-peridotite is the usual variety. Rocks of 

 this class have been called hornblende-picrites by Bonney^ and 

 hudsonites by Cohen,^ but since picrite was originally used for an 

 olivine-augite rock and hudsonite for a variety of diallage, Williams'' 

 proposed for them the name cortlandtite. 



A rock whose present mode places it in Family 5 is scy elite 

 JuDD.^ It consists of hornblende 58.5 per cent, serpentine after 

 olivine 22 per cent, mica 18.5 per cent, and magnetite i per cent. 

 Judd says that the hornblende is probably secondary after augite; 

 therefore it possibly should be placed in Family 11. 



Families j, 6, and 10. — In these pigeonholes fall valbel- 

 lite S CHAFER' and some of the olivinites of Sjogren" and 



^ J. S. Diller, " Mica-Peridotite from Kentucky," Amer. Jour. Sci., XLIV (1892), 

 289; also "Peridotite of Elliott County, Kentucky," U.S. Geol. Surv., Bull. 38 

 (1887), p. II. 



^ A. W. Howitt, "The Diorites and Granites of Swift's Creek and Their Contact 

 Zones, with Notes on the Auriferous Deposits," Proc. Roy. Soc. Victoria, 1879. 



3H. Rosenbusch, review of preceding article, Neues Jahrb., I (1881), 221. 



'•R. D. M. Verbeek, Topographische en geologische heschrijving van een gedeelte 

 van Simiatra's Westkusi (Batavia, 1883), p. 304; also "Description geologique de I'lel 

 d'Ambon," Jaarhoek van het Mijnwegen in Nederl. Oost-Indie, XXXIV (1905). 



sT. G. Bonney, "On a Boulder of Hornblende-Picrite Near Pen-y-Carnisiog. 

 Anglesey," Quart. Jour. Geol. Soc, XXXVII (1881), 137. 



^E. Cohen, "Berichtigung bezuglich des 'Olivin-Diallag-Gesteins' von Schries- 

 heim im Odenwald," Neues Jahrb., I (1885), 242. 



7 G. H. Williams, "The Peridotites of the 'Cortlandt Series' on the Hudson River 

 Near Peekskill, New York," Amer. Jour. Sci., XXXI (1886), p. 30, note. 



*John W. Judd, "On the Tertiary and Older Peridotites of Scotland," Quart. 

 Jour. Geol. Soc, XLI (1885), 401-7. 



'Raimund William Schafer, "Der basische Gesteinszug von Ivrea im Gebiet 

 des Mastallone-Thalles," Tscherm. Min. Petr. Mitth., XVII (1897), 512-14. 



''"A. Sjogren, "Om forekomsten af Tabergs jernmalms fyndighet i Smaland," 

 Foren. i Stockh. Forhandl., Ill (1876), 58. 



