550 REPORT OF NATIONAL MUSEUM, 1890. 



specimens like those from Clip, Arizona (72942), which are actually 

 blue from the abundance of the mineral dumortierite, are quite excep- 

 tional. In specimens 70612 and 70613, from Pigeon Point, Minnesota, 

 are shown quartzites somewhat altered by the action of intrusive rocks 

 forced up through them. Specimens 70674, from McDowell County, 

 North Carolina, carries abundant small indistinct garnets, and also 

 white mica, giving it a schistose structure, and affording thus a form 

 intermediate between the quartzites and mica schists. 



Among the hornblende schists there are but few needing especial 

 attention. It will be noticed that these are, as a rule, less finely schis- 

 tose than are the mica-bearing schists, owing to the fact that the min- 

 eral hornblende is itself less finely fissile. The specimens from Wood- 

 bury, Connecticut (36121); Canaan, New Hampshire (29295); and 

 Bavaria (36G60) may be regarded as the more typical forms. No. 29300 

 from Hanover, New Hampshire, carries, it will be noticed, abundant 

 small red garnets. 



The glaucophane schists are perhaps the least abundant of the horn- 

 blendic varieties. They are represented in the collections by samples 

 from the Isle of Syra in the Mediterranean (38626) ; Zermatt, Switzer- 

 land (70177) ; the Anglesey Monument, Wales, England (70421) ; Pegli, 

 Eiviera, Italy (73060) and the more massive form, perhaps an altered 

 eruptive, from near the mouth of Sulphur Creek, Sonoma County. Cali- 

 fornia (39103). 



AmpMbolite is the name given to an extremely tough and often 

 massive rock of obscure origin, and consisting essentially of the min- 

 eral amphibole or hornblende. Specimens 37655, from Chester, Massa- 

 chusetts; 36692 and 38220, from Ardennes and Isere, France; 36690 and 

 36691, from the Erzgebirge, and 36671 and 36672, from Saxony, may be 

 considered as sufficiently typical, the last two as will be noticed carry- 

 ing many garnets. In specimen 70408, from near Bamle, Norway, and 

 37437, from Maryland, the allied mineral anthophyllite takes the place 

 of the ordinary hornblende. No. 38383, from Brandford, Massachusetts, 

 and 701 L4, from Easton, Pennsylvania, differ from the ordinary amphi- 

 bolite in that the varieties of amphibole actinolite and tremolite take 

 the place of the common hornblende. The tremolite rock, it will be 

 noticed, undergoes alteration into serpentine as shown by the adjoining 

 specimen (70123). 



Eelogite is a tough, massive or slightly schistose rock consisting of 

 the grass-green variety of pyroxene omphacite and small red garnets, 

 with which are frequently associated bluish kyanite, green hornblende 

 (smaragdite), and white mica (See specimen 34670 and 35876) from 

 Bavaria and California. Garnet rock or garnetite is a crystalline gran- 

 ular aggregate of garnets with black mica, hornblende, and magnetite 

 (Specimen 36851, from North Carolina). Kinzigtete is a somewhat 

 similar, though fine grained, and compact, rock consisting of garnets, 

 plagioclase, feldspar, and black mica, and which is found in Kinzig and 

 the Odenwald (specimen 36657). 



