. Annual report . g Huronian and Showing Large Phenocrysts of Feldspar The feldspar phenocrysts carefully determined are mainly andesine. ... Anarrow outer rim usually shows zonal intergrowth, with labradorite and andesinealternating. The groundmass consists of plagioclase, augite. olivine, apatite and ironores. The plagioclase is mainly labradorite, showing zonal growth, with acid andcsi:.eforming the outer zones. The olivine is in small grains and most of it appears tohave crystallized before the feldspar. A brownish augite fills the interstices betweenthe feldspar laths in perfect ophitic s
. Annual report . g Huronian and Showing Large Phenocrysts of Feldspar The feldspar phenocrysts carefully determined are mainly andesine. ... Anarrow outer rim usually shows zonal intergrowth, with labradorite and andesinealternating. The groundmass consists of plagioclase, augite. olivine, apatite and ironores. The plagioclase is mainly labradorite, showing zonal growth, with acid andcsi:.eforming the outer zones. The olivine is in small grains and most of it appears tohave crystallized before the feldspar. A brownish augite fills the interstices betweenthe feldspar laths in perfect ophitic structure. Apatite is usually abundant in longneedles. No quartz or micropegmatite was found. In the examination of some sections of normal sill diabase, in addition to thenormal augite, another pyroxene occurs in lesser amount, showing nearly alwaysparallel extinction but in some sections as high as 10°. The maximum interferencecolor is a pale yellow of the first order. The optical character is positive as in the. Fig. 82.—Contact of slate of Cobalt series (H), and Nipissing diabase (D), Bulsch slate underlies the diabase. augite, and a faint pleochroism is shown. The pyroxene is probably enstatite. Theoccurrence of slightly oblique extinction in rare cases is to be explained in its wideaxial angles. Veins With a few exceptions most of the promising silver-bearing veins have been locatedin the Nipissing diabase, unlike the Cobalt area where the great majority of Hie pro-ductive veins are in the conglomerate of the Cobalt series. The most conspicuousexception is the vein in the conglomerate on the Millerett property, which so far hasproved one of the most important in the Gowganda camp. Native silver occurs insmall quantity in the Keewatin near Miller lake, and strong veins of smaltite andniccolite have been found in the Keewatin and conglomerate. Generally the diabasehas been more thoroughly prospected than the Keewatin or Cobalt series, whichshould be worthy of clo
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectminesandmineralresou
