. Annals of the New York Academy of Sciences. Science; Science -- New York (State). 123 ANNALS NEW YORK ACADEMY OF SCIENCES soon effects saturation, but the anorthite enters reactions by which new- compounds are formed from it and its identity is destroyed. The original crystals are thus placed in contact with a solution saturated with albite but lacking anorthite, and with such a solution only pure albite is in equilibrium. At the beginning of the recrystallization of the basalt induced by the passage of heated aqueous solutions, the anorthite molecule appears to have undergone reactions by w
. Annals of the New York Academy of Sciences. Science; Science -- New York (State). 123 ANNALS NEW YORK ACADEMY OF SCIENCES soon effects saturation, but the anorthite enters reactions by which new- compounds are formed from it and its identity is destroyed. The original crystals are thus placed in contact with a solution saturated with albite but lacking anorthite, and with such a solution only pure albite is in equilibrium. At the beginning of the recrystallization of the basalt induced by the passage of heated aqueous solutions, the anorthite molecule appears to have undergone reactions by which garnet and datolite and possibly other compounds were produced from it. Albite under the new conditions was stable. Anorthite was therefore continually leached out of the labra- dorite, while albite was deposited in its place, a chief feature of the process being probably a growtli of crystals at the expense of others in the vicinity. Aaiu A/^fta. Fig. 3. Basalt bordered by veiu of albite. prebiiite and natrolite. Albite is developed from tbe labradorite of the basalt. Crystals of prebuite rest upon it and botb are replaced by natrolite. X 35. Slide 127. In figs. 3-7 and in Plate XI, figs. 2, 3, albite is shown in characteristic forms and in typical relations with the basalt and with secondary min- erals. Slide 127, a portion of which is sketched in fig. 3, was taken from a hand specimen in which the ordinary dense basalt is seen to be cut by narrow veins of secondary minerals. Under the microscope, the basalt presents the usual microcrystalline development, and the veins are found to consist of natrolite, prebnite and plagioclase feldspar. The crystals of the last occur in interlocking aggi'Cgates of varying crystallographic orientation. They form borders to the basalt and project at various angles into tbe veins, whose principal filling is natrolite. Crystals mm. in length are not uncommon. Most of the crystals show albite twin-. Please note that these images are ext
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1879
