572 PROCEEDINGS OF THE NATIONAL MUSEUM. tol. 39. 



complete repression of the brachydomes g(Oll) and i(031). This 

 phase, too, shows what appears to a less extent among most all the 

 crystals, namely, striated side pinacoid faces, due to oscillatory com- 

 bination of &(010) and m(llO). The ^(301) faces in all three phases 

 are frequently lightly striated horizontally. 



2. A BIOTITE-PHLOGOPITE-RUTILE INTERGROWTH SHOWING 

 ASTERISM FROM OTTAWA, CANADA. 



The regular growth of one mica within another is a not infrequent 

 occurrence. Inclusions of biotite in muscovite, and muscovite in 

 biotite, of lepidolite in muscovite and the reverse, and of biotite in 

 phlogopite, are known from a number of localities. For example, 

 biotite in muscovite from Alstead, New Hampshire, and biotite 

 inclosed in phlogopite from South Burgess and Grenville, Canada, 

 and West Chester, Pennsylvania, have been described by Rose." La- 

 saulx ^ has given a full account of intergrowths of muscovite and 

 biotite occurring at Middletown, Connecticut. Lewis '^ has discussed 

 the inclosures of biotite in muscovite among the micas of West Phila- 

 delphia. Sheets of muscovite containing hexagonal plates of biotite 

 have been noted by Leidy*^ from Macon County, North Carolina. 

 Kunz* has mentioned that slender crystals of biotite were found 

 inclosed in muscovite at Stoneham, Maine. Bowman^ has discussed 

 in detail the intergrowths of muscovite and lepidolite occurring at 

 Haddam Neck in Connecticut. Of these and additional examples, 

 specimens from Middletown, Connecticut; hexagonal sheets of biotite 

 included in muscovite from Buck Creek, Macon County, North Caro- 

 lina; rhombic plates of muscovite in biotite from Custer County, 

 South Dakota; and intergrowths of muscovite and lepidolite from 

 Mount Apatite, Auburn, Maine, are represented in the U. S. National 

 Museum collections.^' The various inclusions vary from several 

 inches in diameter to those of microscopic dimensions, and appear 

 mostly as thin plates within larger sheets, with mutual regularity of 



oG. Rose. Ueber die regelmassigen Verwachsungen der verschiedenen GHmmer- 

 arten unter einander sowie mit Pennin und Eisenglanz. Monatsb. kon. preuss. Acad., 

 Berlin, 1869, pp. 339-362. 



b A. V. Lasaulx. Ueber eine Verwachsung zweier Glimmer von Middletown, Con- 

 necticut. Neues Jahrb. Min. Geol. Pal., 1878, pp. 630-635. 



cH. C. Lewis. On some inclosures in muscovite. Proc. Acad. Nat. Sci. Phila., 

 1882, pp. 311-315. 



dj. Leidy. On topaz and biotite. Proc. Acad. Nat. Sci. Phila., vol. 34, 1882, p. 261. 



«G. F. Kunz. Minerals from Stoneham, Maine. Amer. Jour. Sci., vol. 27, 1884, 

 pp. 212-216. 



/H. L. Bowman. On an occurence of minerals at Haddam Neck, Connecticut, 

 U. S. A. Mineral Mag., vol. 13, 1902, pp. 77-121; Zeitschr. f. Kryst., vol. 37, 1903, 

 pp. 97-119. I 



g Catalogue numbers 14349, 13699, 83775, and 80230, respectively. 



