. The geology of the goldfields of British Guiana. AMPHIBOLITE, x 12,WARIRI, CUYUNI RIVER. Fhoto by J. HORNBLENDE SCHIST, x 40,ITABALLI, MAZARUNI RIVER. Photo hi/ J. IfiUiaiiis. The P(ftrograp]iu of Om Fundamental Gneissose Complex. 45 hornblende are poikilitic in structure, while in a few cases they retainthe ophitic structure which characterised the pyroxene from which theyhave been derived. Not unfrequently, as in specimens from the BlueMountains and from the Mazaruni-Puruni district, the light-colouredmasses of hornblende- surround kernels of almost colourless pyroxene,usually a
. The geology of the goldfields of British Guiana. AMPHIBOLITE, x 12,WARIRI, CUYUNI RIVER. Fhoto by J. HORNBLENDE SCHIST, x 40,ITABALLI, MAZARUNI RIVER. Photo hi/ J. IfiUiaiiis. The P(ftrograp]iu of Om Fundamental Gneissose Complex. 45 hornblende are poikilitic in structure, while in a few cases they retainthe ophitic structure which characterised the pyroxene from which theyhave been derived. Not unfrequently, as in specimens from the BlueMountains and from the Mazaruni-Puruni district, the light-colouredmasses of hornblende- surround kernels of almost colourless pyroxene,usually augite, but in some of the rocks from the Blue Mountains thekernels consist of enstatite or of bronzite. In places the hornblendehas become actinolitic, and is frayed out towards its edges into minutecrystals of colourless amphibole, which in cases appear to run instreams from and round the aggregates of the mineral. The feldspar is usually a more or less basic labradorite, which insome specimens retains it crystalline form, the laths, however, beingmore or less sericitised. More usually it occurs as either c
Size: 1584px × 1578px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectgeology, booksubjectp
