492 University Geological Survey of Kansas. 
Cerussite; ‘‘Dry BONE.’’ 
Composition, lead carbonate, PbCOs: Pb,77-52%; C, 4.48%. Hardness, 
3-83-35; gravity, 6-46-6-48; celor, white, gray, varying through shades of 
blue and green; crystallization, orthorhombic; cleavage, prismatic. 
Observed forms: b(001)OP; c(010) co Po ; a(100) o Po ; 
d(130)@P3; m(110)oP; i(012)$P™; 7(021)2P0; 
7(031)3P.© ; 7(102)$4P © ; $(112)4P; p(111)P. 
The following diagram shows the distribution of forms on 
the crystals measured : 
FORMS. 
Crystal 1. —{/e}—]—|m|{i}|—|—|—]|]—|] p 
Crystal 2. —|ec}]—{—|m]|—]|z/]—|—|—! p 
Crystal 3. bic |—|—| mii |—|r7}]—I 8 /— 
Crystal 4. b}|c}as}d{|mi{i {—j|—|—|—|] p 
Crystal 5. bie} a | — hm |) a) ey Sp 
The brachypinacoid c(010), which is universally present, 
is always horizontally striated. Figures 67 and 68 represent 
two cerussite crystals, the first of which is a very usual com- 
bination. | 
Twins are very common, the twinning plane being the unit 
prism m(110). They are often repeated, giving six-angled 
stellate groups. Twin crystals of cerussite with d(130)  P3 
as the twinning plane, are mentioned by Pirsson & Wells” 
from Granby. 
Cerussite occurs as pseudomorphs after galena and calcite, 
the latter being found only at Granby. 
It usually occurs as small crystals in cavities formed by the 
decomposition of galena, also in white fibrous masses and 
earthy forms. 
The color varies from white to various shades of yellow, 
green, and brown. Black crystals are often noticed. 
ee ee ee i ow 
18. Amer. Jour. Sci., 48 (4), p. 219 (1894). 
