BELTED -RA^GE, ECONOMIC GEOLOGY. 
ite. Sulphides are sparingly present and consist of pvrite, chalco- 
pyrite, galena, and zinc blende, named in the order of their abun- 
dance. From these hematite, limonite, malachite, azurite, and cerus- 
site are derived as secondary minerals. A coating of an unctuous 
mineral in silvery tablets frosts some of the cavities. The values in 
this locality are said to be gold with less silver. The deposit 
genetically similar to the mineralized pegmatite veins of Lime Point, 
in Slate Ridge, and the sulphides were probably introduced into the 
pegmatitic quartz after its solidification. 
The pegmatitic quartz veins abundant in a small granite mass 
three-fourths of a mile east of south of Oak Spring contain pyrite 
crystals, as do the less acidic pegmatites and the surrounding and 
genetically related granite. The quartz is said to carry good gold 
and silver values, presumably in the pyrite. 
About 300 yards southwest of Oak Spring and down the same ridge 
is a 25-foot shaft in Pennsylvanian limestone, here locally horizontal. 
A vein 2 feet wide, which strikes N. 35° E. and dips 70° NW., cuts 
the limestone. The vein is formed of malachite, chrysocolla, and a 
jaspery quartz, which is deeply stained by blotches of manganese 
dioxide and limestone. Striking vugs in malachite lined with later 
azurite which in turn is covered with clear quartz crystals resemble 
copper-sulphate crystals. Massive yellowish-gray cerussite (lead car- 
bonate) is also present. A yellowish -green, finely scaly coating on 
fractures was determined by Mr. Waldemar T. Schaller to be either 
emmonsite or durdenite, hydrated ferric tellurites. The presence 
of the compound of tellurium is of considerable interest, since it indi- 
cates the presence of a telluride among the original minerals of the 
post-Jurassic ore deposits. Emmonsite is one of the last secondary 
minerals to form and coats both jaspery quartz and chrysocolla. 
I Postmineral faulting has occurred. The secondary minerals, which 
alone are seen, partly replace the limestone and partly fill preexist- 
i ing cavities. 
The so-called turquoise mine at Oak Spring is a small cut in the 
metamorphic Pennsylvanian limestone H miles south of the spring 
and three-fourths of a mile from the granite contact. Two veins 
j strike north and south and dip G5° W., apparently parallel to the 
bedding of the limestone, which is here partially marmorized and 
1 silicified. The wider vein varies in width from 2 inches to 1 foot and 
can be traced several hundred feet. Four feet away is a parallel 
vein, the two being connected by a few chrysocolla stringers. The 
veins are composed of a mottled mosaic of chrysocolla and a dark 
compact jaspery quartz, stained in some places by limonite and in 
others by manganese dioxide. The chrysocolla is usually verdigris 
green, although picked pieces are a beautiful robin's-egg blue. The 
Bull. 308—07 m 9 
