210 



University of California. 



I Vol,. 8. 



Physical Properties. — An examination of the crushed massive 

 material on the stage of the microscope showed several roughly 

 square cleavage plates (parallel to the base) which, with con- 

 vergent light, showed a biaxial interference figure with a large 

 angle. From a study of this figure the following facts were 

 ascertained. The optic axial plane is parallel to the clinopina- 

 coid. The bisectrix emerging nearly normal to the base is an 

 axis of maximum elasticity. The mineral boothite agrees thus 

 with melanterite and pisanite and like them is probably positive, 

 the obtuse bisectrix emerging on the base. 



The cleavage is basal, imperfect, Several of the long fibrous 

 fragments show numerous cracks parallel to the base and trans- 

 verse to the direction of elongation. The hardness of the 

 mineral is 2 to 2.5, and the specific gravity about 2.1. The 

 color is blue, like chalcanthite, except perhaps a little paler blue. 

 Many of the specimens have whitened on exposure to the air, 

 showing that the mineral is probably unstable in dry air. In 

 the fibrous pieces the luster is decidedly silky or pearly, while in 

 the more massive variety it is vitreous. 



Chemical Properties. — The mineral is readily soluble in cold 

 water, and in its pyrognostic characters behaves like chalcan- 

 thite. It does not fuse iu a closed tube, but whitens, and 

 finally, upon strong ignition, becomes black. 



Two analyses of fresh material were made, one of the fibrous 

 fragments and one of the more massive material. Both lead to 

 the same formula. The water was weighed direct in a calcium 

 tube, and the copper determined in the usual volumetric way. 

 The mean analysis of the fibrous fragments gave: 



CuO 

 PeO 



Analysis. 

 2(3.80 



Iiisol. deducted. 



27.83 



Ratio. 



1.00 



Calculated. 



27.85 



trace 



trace 



SO ;l 27.32 

 H 2 (105°) 35.29 

 H,0 (above 105°) 7.14 

 Insol. 3.70 



36. G4 



28.37 



7.42 



5.80 



1.00 



1.19 



28.02 



37.83 



6.30 



100.25 



100.26 



100.00 



