Bulletin . is especially true of an abandoned prospect in an old field about one-fourth of a mile southwest of the store at Eed Bank. In the material onthe dump at this place a cream-colored feldspar, probably albite, is secondin abundance as a gangue mineral only to quartz. In the Eed Bank goldmine albite and a delicate pink feldspar, probably orthoclase, occur fre-quently in stringers and veinlets in the ore and in the associated rock. Orthoclase.—A delicate pink or flesh-colored feldspar, which, so far asmethods of identification could determine, in the absence of chemicalanalys
Bulletin . is especially true of an abandoned prospect in an old field about one-fourth of a mile southwest of the store at Eed Bank. In the material onthe dump at this place a cream-colored feldspar, probably albite, is secondin abundance as a gangue mineral only to quartz. In the Eed Bank goldmine albite and a delicate pink feldspar, probably orthoclase, occur fre-quently in stringers and veinlets in the ore and in the associated rock. Orthoclase.—A delicate pink or flesh-colored feldspar, which, so far asmethods of identification could determine, in the absence of chemicalanalyses, is orthoclase, which is found as a gangue mineral in the Holloway,Durgy, and Blue Wing mines, and in considerable amount in the two Corn-field prospects Just south of Virgilina. In the first-mentioned places themineral was not found in actual contact with the ores, but in the Cornfieldprospects it serves as a host mineral for all the difierent hypogene sulphides. VIRGINIA GEOLOGICAL SURVEY. PLATE rhotograph of a polished .surface of ore from the Seaboard mine, xlO. This .speci-men shows a mass of bornite penetrated in all directions by a mesh or net-work of chalcocite which has formed in fractures in the bornite. This typeof chalcocite is clearly of supergene origin and is typical of all such chalcociteexamined, the only difference being the stage of development. This one isfarther advanced than any of the others shown in this report. The line inthe center of many of the chalcocite veinlets is quartz and marks the positionof the fracture in which the chalcocite began to develop. Running diago-nally across the specimen is a more recent fracture which cuts botli^borniteand chalcocite veins. A tiny veinlet of chalcocite has formed in this fracture. DETAILED DESCRIPTION OF THE VEINS AXD ORES. 73 It frequently occurs in the form of small veins or stringers in the countryrock in the vicinity of the veins. It is also fairly abundant in the Red Bankgold mine, occurring in a
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