EXCEPTIONAL VARIETIES OF VEINS. 
183 
CELESTITE VEIN. 
The only occurrence of a celestite vein was found in level 7 of the Ironclad mine, 
where the crosscut to the main vein intersects a massive vein about 1 foot wide 
and striking northeasterly. The vein, which is poor in gold, but is said to carry 
some lead, contains streaks of limonite and clay, but consists chiefly of white 
granular celestite, coated with chalky crusts of a hydrous sulphate of strontia. 
BIOTIT E-FELD SPAR VEIN. 
A biotite-feldspar vein, the only one of this very remarkable type, was found 
in the Ophelia tunnel, about G,000 feet from the portal, in the Dolly Yarden 
claim. Penrose® mentions a possible similar occurrence on the Ocean Wave 
claim, which coidd not be definitely located, but gives no details. The vein, which 
crosses the tunnel with a general northerly direction, appears as a zone oi narrow 
but well-defined stringers, the aggregate thickness of which is 6 to 10 feet. They 
consist of white drusy feldspar ; pyrite, partly with crystal outlines, and black 
biotite, the latter in well-crystallized hexagonal prisms. All three minerals are 
intimately intergrown; pyrite and small foils of biotite are disseminated for some 
distance into the surrounding rock, which is sharply separated from the vein filling. 
The feldspar consists of coarsely granular orthoclase with narrow intergrown 
lamellae of albite. An analysis of the feldspar by Mr. George Steiger yielded 13.27 
per cent Iv 2 0, 1.36 per cent Na 2 0, and 0.04 per cent CaO. The biotite lies embedded 
in the feldspar as large ragged foils of pale yellowish-brown color and wide axial 
angle. The pyrite contains only 0.08 ounce of gold and 0.20 ounce of silver per 
ton. The whole occurrence is very unusual. The type of the feldspar with albite 
lamellae is granitic and has not before been observed in distinct veins, to which 
class this deposit undoubtedly belongs. It is not an altered granitic dike. It is 
so entirely different from the other types of deposits in the district that it must 
have been formed under unusual conditions, probably at a greater degree of heat 
than prevailed during the principal vein-forming epoch. 
a Sixteenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1895, p. 129. 
