ORES OF LEAD. 149 
Mts., and in Yuma County; in the Castle Dome, Eureka, 
and other districts, where the ore is worked for the silver it 
contains. 
The lead of commerce is obtained from this ore. It is 
also employed in glazing common stoneware: for this pur- 
pose it is ground up to an impalpable powder and mixed in 
water with clay; into this liquid the earthen vessel is dipped 
and then baked. 
Lead Selenides and Tellurides. 
These various ores of lead are distinguished by the fumes before the 
blowpipe, and by yielding, on charcoal, ultimately, a globule of lead. 
Clausthalite, or lead selenide, has a lead-gray color, and granular 
fracture, and is occasionally foliated. H.=2°5-3. G.=7-6-8°8. B.B. on 
charcoal a horse-radish odor (that of selenium). From the Hartz. 
There is a lead and copper selenide (Zorgite) which has the sp. er. 
7-75. <A lead-and-mereury selenide (Lehrbachite) occurs in foliated 
grains or masses of a lead-gray to bluish and iron-black color. 
Altaite, or lead telluride. A tin-white cleavable mineral, with H.=3 
-3'd, and G.=8'16. From the Altai Mountains. 
Nagyagite, or Foliated tellurium, is a less rare species, remarkable 
for being foliated like graphite ; color and streak blackish lead-gray ; 
H.=1-1°5, G.=7-085. It contains Tellurium 82:2, lead 54:0, gold 9:0, 
with often silver, copper, and some sulphur. From Transylvania. 
Antimonial and Arsenical Sulphides of lead. These include Sartorite, 
Zinkenite, Plagionite, Jamcsonite, Dufrenoysite, Boulangerite, Kobel- 
lite, Meneghinite, Geocronite ; also Brongniardite and Freieslebenite, 
in which silver is also present, and Stylotypite and Atkenite in which 
copper is also present. 
Minium.—Oxide of Lead. 
Pulverulent. Color bright red, mixed with yellow.. G.= 
4:6. Composition, Pb, O,. Affords globules of lead in the 
reduction flame of the blowpipe. 
Obs. Occurs at various mines, usually associated with 
galena, and is found abundantly at Austin’s Mines, Wythe 
County, Virginia, with white lead ore. 
Uses. Minium is the red lead of commerce ; but for the 
arts it is artificially prepared. 
Plumbic ochre is lead protoxide, of a yellow color. 
Mendipite. Color white, yellowish or reddish, nearly opaque. Lustre 
pearly, G.=7-7'1.. Bb Cl, + Pb O= Chloride of lead 38°4, lead oxide 
61-6. From Mendip Hills, Somersetshire. Cotunnite is a chloride of 
lead, Pb Clo, occurring at Vesuvius in white acicular crystals. It con- 
tains 74:5 per cent. of lead. 
Plumbogummite. Yn globular forms, having a lustre somewhat 
like gim arabic, and a yellowish or reddish-brown color. H.—4-4°5. 
