ere ic: 
OF ARKANSAS. 153 
it has certainly been derived from the red clay, filling the cavities of the 
ore. 
No. 9. Compact smithsonite, incrusting dolomite. 
Composition, dried at 212 deg. F: 
Quartz... eee eee eens See eee eee eee eee ees 1.512 
Oxide of zinc. ..++....06. a Ae Rea Oa a eas 65.967 
SC TRON ss ee ees eae ewe Se nee a oe trace 
LAC. 48.644 6466 4 view POS HA OT S68 REED ERS 1.067 
Magnesia. +++. eee e cece e cece eee e ences trace 
Carbonie acid, and loss:-+++++seeeeeeeeeees 81.454 
100.000 
The air-dried mineral lost 0.116 per cent. of moisture at 212 deg. F. 
From the high per centage of oxide of zinc in this mineral, it would 
appear to be a basic carbonate of zinc, but as no direct carbonic acid 
determination was made, it is not, at present, possible to construct a for- 
mula for its composition. 
Rounded pieces of dark-gray, subcrystalline dolomite appear, sometimes, 
as if cemented by carbonate of zinc, which surrounds the fragments in 
concentric, incrusting layers. The carbonate of zinc is of grayish, brown- 
ish, or reddish color; between its layers, but mostly between the dolomite 
and the carbonate of zinc, a white mineral is occasionally observed, whose 
properties and composition are given in No. 10. 
No. 10. Martonrrz, a new hydrous carbonate of zinc. 
Occurs in concentric and contorted lamine, also, in botryoidal and mam- 
milated incrustations; amorphous; earthy; color milk-white; hardness 2.5; 
easily reduced to powder; powder milk-white. 
Dissolves readily, and completely, in cold dilute hydrochloric acid, with 
effervescence; also, when pulverized, in ammonia; in both solutions, sul- 
phydrate of ammonia produces a white precipitate. Heatedin a matrass, 
yields water and turns yellow; heated before the blowpipe with a solution 
of nitrate of cobalt, assumes a bright green color; on charcoal, behaves like 
oxide of zinc. 
On being ignited in a platina capsule, the mineral lost 26.818 per cen 
the residue, dissolved in hydrochloric acid, and the solution precipitated 
with carbonate of soda, gave 73.262 per cent. of oxide of zinc. 
Carbonic acid and water--+-++-+-+> teeeeees 26.818 
Oxide of Zinc ss sseerees cere ese eeseeeeeees 73.262 
100.080 
