VADOSE ORE DEPOSITION 
385 
vast areas and are everywhere characterized by the presence of 
copper and other metals. Part of the copper is held by wood 
and plant remains; but the ores when forming workable deposits 
appear to be mainly interstitial. In the few cases in which the 
structure has been made out with this relationship clearly in 
mind, a well-defined basin has been determined; and beyond its 
limits where impondment conditions do not occur there has been 
no deposition of the chalcocite ore. This is shown in the Han- 
sonberg and Palomas Gap deposits in central New Mexico; 
along the San Pedro arroyo east of the Sandia range; at Abiquiu, 
in northern New Mexico; at Copperton in the Zuni district; and 
about Tecolote, west of Las Vegas, as well as at many other 
places in New Mexico, Arizona and Colorado. At Tecolote the 
sandstones are not “red-beds” however, and the distinct faulting 
on inclined strata has clearly produced local imponding-conditions. 
Since there are in all these deposits appreciable amounts of 
silver it is quite probable that the formation of the copper ores 
is similar to that which I have recently ascribed to the cerargyritic 
ores of dry regions generally. A like origin seems to belong 
to the copper-bearing sandstones of the Permian series which 
lie on the west flank of the Ural mountains in Russia, as des¬ 
cribed by Krasnopolsky ; and perhaps also to the Zechstein 
deposits of Mansfeld, Germany, although not on the grounds 
advanced by Beyschlag The disseminated coppers of the 
Corocoro, in Bolivia, appear to belong here, although the mines 
are upwards of 1400 feet deep, as long ago mentioned by Forbes 
The Silver Reef mine, in Utah, contains native silver and cerarg- 
yrite above groundwater-level and argentite below as interstitial 
ore-materials in Triassic sandstones, as reported by Cazin 
Disseminated ore-bodies may be formed by the distribution of 
ore-materials through the interstices of rock-components; or they 
may be due to the occurence of the metallic salts among the frag¬ 
ments of brecciated belts. Although variously formed, breccias 
all present a common feature, so far as ore-deposition is con¬ 
cerned. Whether they are formed by crushed masses, as in the 
case of limestones undergoing dolomitization, by close jointing 
14 Economic Geology, Vol. II, p. 774, 1907 . 
15 Mem. Com. G6ol. Russie, T. XI, No. 1, 1889. 
16 Zeitschrift fiir Praktische Geologic, 1900, p. 115. 
17 Quarterly Jour. Geol. Soc. London, Vol. XVII, p. 41, 1861. 
18 Eng. and Mining Jour., Vol. XXXIX, p. 351, 1880. 
