200 KANSAS CITY REVIEW OF SCIENCE. 
THE ORIGIN AND CLASSIFICATION OF ORE DEPOSITS.* 
BY PROF. J. S. NEWBERRY. 
(Concluded. ) 
Mineral Veins. Some writers on economic geology—Werner, Von Cotta and 
Von Groddeck, for example—enumerate many different kinds of mineral veins ; 
but disregarding the local characters which all ore-deposits exhibit and the hy- 
brids which are formed by the blending of two distinct forms, not of uncom- 
mon occurrence, I agree with Whitney in recognizing but three dis'inct classes, 
namely : 
I. Gash-veins. 
2. Segregated veins. 
3. Lissure-veins. 
Gash-veins may be defined to be those which occur only in limestone, are 
confined to a single stratum formation, and hence are limited in extent, both 
laterally and vertically. Typical examples of gash-veins are furnished by our lead 
deposits of the Mississippi valley. These occur at three horizons, namely, about 
Galena, in the Galena limestone, belonging to the Trenton group; in Southeast- 
ern Missouri, where the Mine La Motte is located, in the equivalent of the Cal- 
ciferous sand-rock; and in Southwestern Missouri, where the mines of lead and 
zinc occur in the Lower Carboniferous limestone. The origin of deposits of this. 
character is apparently quite simple. ‘The cavities which form the repositories of 
the ore are generally the cleavage-planes or joints of a soluble limestone rock that 
become channels through which surface-water charged with carbonic acid flows 
in a system of subterranean drainage. We usually find two sets of joints approx- 
imately at right angles to each other, and vertical if the rocks are horizontal. To 
form gash-veins, one or both of these sets of vertical joints are locally enlarged 
into lenticular cavities or ‘‘ gashes,”’ whence the name; but sometimes caves of 
considerable size, irregular pockets, and vertical or horizontal galleries are formed. 
These are subsequently lined or filled with ore, sulphides of lead, zinc, and iron, 
originally disseminated through the limestone, and leached out of it by water, 
which saturates and traverses all rocks in a humid climate. The solution thus 
formed reaching a cavity has, by evaporation, deposited the ore asa lining to 
that cavity; narrow fissures being perhaps filled, walls of larger cavities coated 
with stalactites depending from the roof, etc. Subsequent solution has sometimes 
widened a fissure once filled with ore, leaving the ore-body as a central partition, 
a curtain more or less complete hanging from the roof, or a mass of fragments 
mingled with infiltrated sand and clay in the floor of the cave. In Southwestern 
Missouri, the Carboniferous limestone contains layers of chert, which are insolu- 
ble, and which sometimes form horizontal floors or ceilings of caverns. These, - 
*From the School of Mines Quarterly, March, 1880. 
