MINERALOGY OF THE PACIFIC COAST. 5 



inclination of the acute bisectrix to the normal of the base; 

 while this vahie amounts to 12°-16^ in clinochlor, it has 

 been measured to 1°-'2P in kotschubeite,. v. Leuchten- 

 berg's description applies entirely to the California occur- 

 rence as to the optical characters, but the crystal form 

 differs. The mineral from Ural had the form of hexagonal 

 jDyramids, and was apparently composed of simple crystals, 

 while that here described occurs as thin tables composed of 

 three individuals, twinned according to the well known law of 

 clinochlore, so as to appear as hexagonal crystals. In the 

 position of the optical axis the crystals most resemble those 

 of clinochlore from Texas, Pa., described by Cook. 



A further and notable difference from Kokscharow's 

 kotschubeite, and indeed from any known chromiferous 

 <ihlorite, is in the very high percentage of Crg Ogj v. Leuch- 

 tenberg found 4.09 %, while the highest percentage of 

 of Cr2 O3, in kiimmereite is 5.50 %. 



The analysis of the California mineral shows more than 

 twice that amount, viz. : 11.392 per cent, Crg O3 replac- 

 ing AI2 O3, but in other respects agrees well with those 

 of kammererite and kotschubeite given above for com- 

 parison. Nearly half a per cent, of Ni^O also enters into 

 the composition of the mineral; it is similar in this respect 

 to kammererite, which often also contains a small amount of 

 this metal. 



In the collection of the State Mineralogical Museum, 

 there is one specimen of chromite from near Jackson, Ama- 

 dor County, covered by a thin coat of massive, peach blos- 

 som colored chromiferous chlorite. Whether it is kiimmer- 

 ■erite or kotschubeite, is diiiicult to decide. 



2. Uwarowite. 



Together with the kotschubeite, mixed with it as small 

 grains or lining small fissures in chromite as almost micro- 

 scopic crystals with brilliant faces, there occurs a deep em- 

 erald-green garnet. Under the microscope the crystals 



