KINDS OF ROCKS. 75 



3. Epidosyte. — Pale green to pistachio-green. Epidote mixed with quartz. 



4. Euphotide (Gabbro, in part). — Whitish to greenish; compact and tough. Made 

 up of compact saussurite, which is usually near labradorite in composition but has sp. 

 gr. = 3 or above, and smaragdite, a light green, lamellar hornblende that is sometimes 

 changed to pyroxene. Often contains serpentine. Occurs in the Alps, etc. 



5. Eulysite. — Fine-granular, consisting of chrysolite with a diallage-like mineral 

 and garnet. Forms a bed in gneiss near Tunaberg, Sweden. 



6. Chrysolite-kock, or Chrysolyte. — Yellowish to pale olive-green, granular; 

 consisting almost wholly of chrysolite. Sp. gr. 3-3*1 ; H. 5"5-6. Abundant in Macon 

 Co., N. Carolina ; in part changed to serpentine. For Dunyte, which is supposed to be 

 eruptive, and also Lherzolyte, Picryte, Limburgyte, see p. 79. 



5. Hydrous Magnesian and Aluminous Rocks. 



Contain one or more of the hydrous magnesian minerals, chlorite, talc, serpentine; or 

 the related hydrous aluminous mineral, pyrophyllite. The series commences in a 

 granitoid or gneissoid species. The fine-grained kinds are more or less greasy to the 

 touch; and some of them resemble the hydromica slates. 



1. Protogine. A gneiss-like or granitoid rock consisting of orthoclase, quartz, and 

 mica, with talc. Color grayish-white, greenish-white, and greenish-gray. Porphy- 

 ritic, micaceous, and vligoclase-bearing varieties occur. 



2. Chlorite Schist or Slate. — Schistose ; color, dark green to grayish-green and 

 greenish-black ; but little, if any, greasy to the touch. Consists of chlorite, with 

 usually some quartz and feldspar intimately blended, and often contains crystals 

 (usually octahedrons) of magnetite, and sometimes chlorite in distinct scales or concre- 

 tions. 



Varieties. — a. Ordinary, b. Hornblendic ; the hornblende in grains or needles. 

 c. Magnetitic. d. Tourmalinic. e. Garnetiferous. f. Pyroxenic. g. Staurolitic. h. 

 Epidutic. Graduates into 



3. Chlorite-argillyie. — An argillyte or clay-slate consisting largely of chlorite. 



4. Talcose Slate. — A slate or schist consisting chiefly of talc. Not common, ex- 

 cept in local beds, most of the so-called " talcose slate" being hydromica slate (p. 72). 



5. Steatyte, Soapstone (p. 55). — Consists of talc. Massive, more or less schis- 

 tose; granular to aphanitic. Color, gray to grayish green and white. Feels very soapy. 

 Easily cut with a knife. 



Varieties. — a. Coarse-granular, and massive or somewhat schistose, b. Fine- 

 granular ; "French chalk." c. Aphanilic, or Eenssekerite ; of grayish-white, green- 

 ish brownish to black colors ; from St. Lawrence Co-, N. Y., and Grenville, Canada. 



6. Serpentine (p. 55). — Aphanitic or hardly granular; of dark-green to greenish- 

 black color, easily scratched with a knife, and often a little greasy to the feel, on a 

 smooth surface. Although generally dark green, it is sometimes pale grayish and 

 yellowish-green, and mottled. 



7. Ophiolyte (Verd-Antique Marble). — A mixture of serpentine with limestone, 

 dolomite, or magnesite, having a mottled green color. Often contains disseminated 

 magnetite or chromite. 



Varieties. — a. Calcareous; b. Dolomitic ; c. Magnesitic. Either of these kinds 

 may contain chromite or magnetite. 



8. Pyrophyllyte and Pyrophyllyte Slate. — Like the preceding in appearance 

 and soapy feel, but having the composition of pyrophyllite (p. 58). The color is white 

 and gray or greenish white. Occurs in North Carolina; one of the varieties from the 

 Deep River region is used for slate pencils. 



6. Iron-Ore Rocks. 



Specular Iron-Ore (Hematite) and Magnetic Iron-Ore occur as rocks of con- 

 siderable thickness among the metamorphic rocks, especially the hornblendic and chlo- 

 ride kinds. There are schistose or laminated as well as massive varieties. Their al- 

 ternation with chloritic and other schists and gneissoid rocks shows that they are met- 

 amorphic as well as the schists. They occur chiefly in Archaean regions; but the upper 



