316 DESCRIPTIONS OF MINERALS. 



Approaches in composition the chlorites, and may belong 

 to that group. 



Qillingite from Sweden, including Thraulite from Bavaria, Epichlo- 

 rite, and Lillite, are other hydrous silicates containing iron. 



Ekmannite y foliated, chlorite-like, occurs in the rifts of magnetite, 

 in Sweden ; it is a hydrous iron silicate, but the iron is mostly in the 

 protoxide state. 



Neotocite (Stratopeite) and Wittingite are results of the alteration of 

 rhodonite, and contain manganese. Btuhelite also contains manganese 

 oxide. 



Strigonte from Striegau, Siberia, and Jollyte from Bodenmais in 

 Bavaria, are hydrous silicates of aluminum and iron, with little mag- 

 nesium. 



CHLORITE GROUP. 



The chlorite group includes the hydrous Suisilicates of 

 the Margarophyllite Section and also some related species 

 that are Unisilicates. The proportion of silica is small, the 

 percentage afforded by analyses being under 38, and mostly 

 under 30. The minerals when well crystallized are foliated 

 like the micas, and have the plane angle of the base of the 

 crystals 120°, but the folia are inelastic and in some species 

 brittle. They also occur in fibrous and in fine granular and 

 compact forms, and the latter are usually most common. 

 Green, varying from light to blackish green, is the prevail- 

 ing color, yet gray, yellowish, reddish, and even white and 

 black also occur ■ and the colored transparent or translu- 

 cent are dichroic. The green color is owing to the presence 

 of iron, and fails only in species containing little or none 

 of it. All of the species yield water in a closed tube. 

 The quantivalent (or combining-power) ratio for R + R and 

 Si is, in the 



Pyrosclerite subdivision 1:1. 



Chlorite subdivision 1 : f, 1 : f , 1 : 1. 



The chlorite subdivision includes Penninite, Eipidolite 

 and Prochlorite, together with some related dark -green to 

 blackish-green species. Some species of this subdivision 

 characterize extensive rock formations, making chlorite 



