1915.1 



NATURAL SCIENCES OF PHILADELPHIA. 



431 



b. Metamorphosed (additional 

 Acid silicates; hydrous: 

 Metasilicates ; amphiboles: 

 hydrous: 



Orthosilicates; epidotes: 

 boro- : 

 hydrous : 



Carbonates : 

 Sulfates : 



Silicate-sulfate-carbonates : 

 Oxides; 2: 3: 

 Sulfides; 1:1: 

 Elements; metallic: 



c. Weathered 



Oxides; hydroxy-: 

 Hydroxides : 

 Silicates; hydroxy-: 



to those of a)^ 



ptilolite, mordenite 



griinerite, glaucophanite 



pectolite; okenite, gyrolite, apo- 

 phyllite; heulandite, brewsterite, 

 epistilbite, phillipsite, harmo- 

 tome, stilbite, gismondite, lau- 

 montite, laubanite, chabazite, 

 gmelinite, levynite, faujasite, 

 eding-tonite, natrolite, mesolite, 

 scolecite, zeophyllite 



zoisite, piedmontite 



datolite 



thomsonite, hydronephelite; law- 

 sonite; prehnite 



calcite, aragonite 



anhydrite; gypsum 



thaumasite 



hematite 



galena, sphalerite 



copper, silver 



limonite, bauxite 



gibbsite 



chlorite (many varieties) , kaolinite 



I. 1. D. Magnesic Igneous Rocks 



a. Primary 



Feldspars ; orthoclases : 

 plagioclases : 

 Metasilicates; pyroxenes: 

 Orthosilicates; garnets: 



chrysolites : 

 Oxides; 2:3: 



double; spinels: 



rare-earth- : 

 Sulfides and arsenides ; 1 : 1 : 



misc. 



(orthoclase) 



labradorite, bytownite 



enstatite, hypersthene, augite 



andradite, pyrope, uvarovite 



olivine, knebelite 



corundum 



spinel (picotite), magnetite, chro- 



mite 

 ilmenite; perovskite 

 pyrrhotite, niccolite 

 sperrylite, chalcopyrite 



* Zeolite veins are regarded as belonging here. 



