Localities of Minerals, &e. 379 
stone, and of calcedonified, and japerized wood : some of which 
are very curious from the perfect preservation of the woo- 
dy texture,—the substitution of silex being so complete as to 
render apparent, not only the horizontal and divergent lay- 
ers of the igneous fibre, but even the vascular texture itself. 
A petrifaction of madrepore by a beautiful white hornstone, 
forms a singular specimen, and appears to be abundant. 
The collection contains also, many masses of sard, calcedo- 
ny, ribbon-agate and jasper-agate, which, (as well as the 
petrifactions just mentioned,) in the hands of the lapidary, 
would, without doubt, afford very beautiful objects of orna- 
ment. CU. 
XILL. Lead Ores of Missouri ; by Messrs. Troost and LE- 
uEUR.—T he lead ores which occur at the mines of Missouri, 
differ somewhat in every mine we visited. The first mine 
we examined was that known by the name of La Motte. The 
ore of this mine is the most complicated of any that we met 
in this district. It is generally the sulphuret of lead (galena, 
or lead glance) and oceurs in masses of various size and grains, 
of an irregular foliated structure, approaching sometimes to 
small curved lamellar, and even granular ; these masses are 
interwoven with carbonate of lead, (white lead ore) in veins 
or small crystals, filling the cavities of the sulphuret of lead, 
and in the earthy state. These cavities are sometimes lined 
with sulphate of lead crystallized in small elongated octahe- 
dra. Besides these accidental mixtures, it is also contami- 
nated with argillaceous iron ore in a pulverulent aud con- 
creted state. : : z 
The carbonate of lead occurs also, erystalized and in an 
earthy state ; the crystalized variety is commonly i ors-. 
ed through the argillaceous oxide of iron, which is very abun- 
dant in these mines. These crystals are generally small ; 
and those which we collected from the rejected rubbish, un- 
determinable. (The earthy carbonate of lead occurs in amor- 
phous masses of an earthy and stony aspect, and incrusting” 
the sulphuret. We found also a great number of fragments 
ofa vein of between one and a half and three inches thick of 
a carbonate of lead, which ha ' 
two parts, one of which is ) f 
lead, of a grayish white color, and an uneven fracture ap~ 
