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The area shown in each slide is approximately 0.9 x 1.2 mm. Olivine phenocrysts are as much as 2 mm in longest dimension, but average close to 0.5 mm. Clinopyroxene crystals are small and equant, rarely exceeding 0.1 mm in length and close to 0.01 mm in their short dimension. Slide 1 shows a cluster of euhedral olivine phenocrysts in a matrix of light brown glass sprinkled with tiny equant pyroxene crystals and a few crystals of plagioclase, which has just begun to crystallize. A flat plate of newly formed plagioclase is seen in one corner of the slide. Published as Slide 1 in U.S. Geological Survey publication titled, Crystallization of basalt in Makaopuhi lava lake, Hawaii: descriptive material to accompany...
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The area shown in each slide is approximately 0.9 x 1.2 mm. Olivine phenocrysts are as much as 2 mm in longest dimension, but average close to 0.5 mm. Clinopyroxene crystals are small and equant, rarely exceeding 0.1 mm in length and close to 0.01 mm in their short dimension. Slide 5 shows an interlocking network of pyroxene, plagioclase, and opaque minerals, the interstices of which are filled with a light-brown glass containing small needles of apatite. Published as Slide 5 in U.S. Geological Survey publication titled, "Crystallization of basalt in Makaopuhi lava lake, Hawaii: descriptive material to accompany of set of 7 colored slides illustrating "Crystallization of basalt in Makaopuhi lava lake, Hawaii"....
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The area shown in each slide is approximately 0.9 x 1.2 mm. Olivine phenocrysts are as much as 2 mm in longest dimension, but average close to 0.5 mm. Clinopyroxene crystals are small and equant, rarely exceeding 0.1 mm in length and close to 0.01 mm in their short dimension. Slide 4 is identical to slide 3 except that a few opaque blades of ilmenite have crystallized. Published as Slide 4 in U.S. Geological Survey publication titled, "Crystallization of basalt in Makaopuhi lava lake, Hawaii: descriptive material to accompany of set of 7 colored slides illustrating "Crystallization of basalt in Makaopuhi lava lake, Hawaii".
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The area shown in each slide is approximately 0.9 x 1.2 mm. Olivine phenocrysts are as much as 2 mm in longest dimension, but average close to 0.5 mm. Clinopyroxene crystals are small and equant, rarely exceeding 0.1 mm in length and close to 0.01 mm in their short dimension. Slide 6 shows a rock collected below the solidus of 990 degree C. Not easily seen in the slide (but evident under a high power microscope objective) are small pools of clear glass that is retained metastably below the solidus. The decrease in intensity of the color of the glass going from slide 4 to slide 6 is caused by a decrease in abundance of iron and titanium, which are taken up in the opaque phases. The large olivine phenocryst...
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The area shown in each slide is approximately 0.9 x 1.2 mm. Olivine phenocrysts are as much as 2 mm in longest dimension, but average close to 0.5 mm. Clinopyroxene crystals are small and equant, rarely exceeding 0.1 mm in length and close to 0.01 mm in their short dimension. Slide 7 shows a rock similar to that of slide 6 but collected at lower temperature in the zone of alteration. The alteration is marked by reddening of the olivine (probably by hematite, as a first stage in the formation of iddingsite) and metasomatic replacement of silicate minerals by opaque phases, as yet unidentified. Published as Slide 7 in U.S. Geological Survey publication titled, "Crystallization of basalt in Makaopuhi lava lake,...
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The area shown in each slide is approximately 0.9 x 1.2 mm. Olivine phenocrysts are as much as 2 mm in longest dimension, but average close to 0.5 mm. Clinopyroxene crystals are small and equant, rarely exceeding 0.1 mm in length and close to 0.01 mm in their short dimension. Slide 3 is taken of a non-porphyritic assemlage of pyroxene cyrstals and plagioclase laths surrounded by glass of a deep reddish-brown hue. This specimen was collected at a temperature just above that of the first appearance of opaque minerals. The change in color of the glass from slide 1 to slide 3 reflects increasing iron and litanium content of glass with falling temperature. Published as Slide 3 in U.S. Geological Survey publication...
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The area shown in each slide is approximately 0.9 x 1.2 mm. Olivine phenocrysts are as much as 2 mm in longest dimension, but average close to 0.5 mm. Clinopyroxene crystals are small and equant, rarely exceeding 0.1 mm in length and close to 0.01 mm in their short dimension. Slide 2 shows a light-colored olivine phenocrysts adjacent to a darker cluster of pyroxene microphenocrysts set in a matrix of glass darker than that of slide 1. Groundmass pyroxene crystals are still small but plagioclase laths are fairly abundant and well formed. Published as Slide 2 in U.S. Geological Survey publication titled, "Crystallization of basalt in Makaopuhi lava lake, Hawaii: descriptive material to accompany of set of 7 colored...