F. A. Genth — Contributions to Mineralogy. 117 



garnet, associated with magnetite, pyrite and remnants of the 

 essonite. The crystals are columnar, the best are the smallest 

 and show combinations of the 1st and 2d prism with the basal 

 pinacoid ; no pyramidal planes could be observed. The larger 

 crystals are deeply striated, by which all planes are obliterated. 

 Their size varies from 2 mm in length and 0-25 mm in thickness to 

 20 mm in length and 5 mm in thickness ; frequently in groups. 

 Colorless to white and grayish white. Spec. grav. = 2-675. 

 The analyses gave : 



a b 



Loss by ignition 1*50 1*51 



C0 2 _. 2-63 not det'd 



Si0 2 52-30 52'26 



A1 2 3 ... ... 23-68 24-15 



Fe 2 3 0-58 0-43 



MgO 0-05 0-16 



CaO 12-36 11-76 



Na 2 6-29 not det'd 



K,0 0-77 " " 



100-06 



7. Garnet. 



This garnet which results from the alteration of essonite 

 shows occasionally dodecahedral and trapezohedral planes which 

 are sometimes coated with a thin shell (not over 0'5 mm in thick- 

 ness) of the original mineral of a bright cinnamon-brown 

 color. The purest has a brownish gray or ash-gray color and a 

 spec. gr. of 3-390. The analysis gave: 



a 



Loss by ignition 0*51 



C0 2 1-71 



Si0 2 .... 41-42 



A1 2 3 18-09 



Fe„0 3 10-81 



MnO '. 0-88 



MgO 0-59 



CaO 26-19 



b 



ot det'd 



41-69 



18-37 



10-27 



0-93 



0-52 



26-10 



100-20 



8. Titaniferous Garnet. 



The late Thos. S. Ash brought from the Jones Mine on 

 Green River, Henderson Co., N. C, a variety of garnet which 

 I have analyzed. 



It is massive, of a splintery uneven fracture, has only slight 

 indications of dodecahedral planes, brown color, spec. grav. 

 = 3*738. The analysis gave : 



