CHAPTER VIII 



OXIDES, INCLUDING THE ALUMINITES, FERRITES, 

 CHROMITES 



OXIDES OF THE RO TYPE 



WATER 



Water. Ice; Snow; Frost; H 2 O; H = 11.1, O = 88.9; 

 Hexagonal; Typo, Dihexagonal Alternating; c = 1.4026; 

 0001 A lOll = 58 18' ; Common forms, c (0001), m (1010), r (1012) ; 

 H. = 1.5; G. = .9167; Luster, vitreous; Transparent; Color, 

 white when pure, but blue in large masses; co = 1.3090; 

 = 1.3133; Optically (+). 



B.B. Fuses at 0, volatilizes entirely, leaving no coat and yield- 

 ing no odor. 



General description. Crystals with individual faces rare ; 

 sometimes they occur on hailstones. Usually complex stellate aggre- 

 gates produced by twinning; occurs during low temperature as 

 frost, snow, and sheets of ice covering lakes and streams. In the 

 high latitudes it forms the permanent polar ice cap. In Alaska sheets 

 of geological ice occur interbedded with sedimentary deposits. 

 Glaciers are streams of ice moving from the perpetual snow-covered 

 mountain ranges to lower altitudes. 



CUPRITE 



Cuprite. Red oxide of copper ; Cuprous oxide, Cu 2 O ; Cu = 

 88.8; O = 11.2; Isometric; Type, Tesseral Holoaxial ; Common 

 forms, a (001) ; o (111) ; d (110) ; Cleavage, octahedral imperfect ; 

 Brittle, fracture conchoidal ; H. = 3.5^1; G. = 5.85-6.15; Luster, 

 adamantine to earthy; Color, cochincal-ivd to nearly black; 

 Streak, shades of red or brown ; Transparent on thin edges to 

 opaque; n = 2.849. 



B.B. Fuses and in R. F. yields malleable copper, and an emer- 

 ald green flame. With the fluxes shows copper. Easily soluble 

 in acids. 



z 337 



