Proceedings of the United States National Museum . + 5i Fig. T.—Calcite. Habit of smallyellowish to amber crystals yellowish transparent crystals of the form (33 61) was then intro-duced, these averaging 5 millimeters in length. One small vug inthis seam was filled with chalcedony. Some specimens show datolite resting on coarse granular bluishcalcite which is apparently older than the datolite. Most of thecalcite crystals are, however, distinctly younger and rest upon the ART. 28 MINERALOGY OF TRIASSIC LIMESTONE SHANNON 29 datolite. The first and simplest type of these forms transparent paleam
Proceedings of the United States National Museum . + 5i Fig. T.—Calcite. Habit of smallyellowish to amber crystals yellowish transparent crystals of the form (33 61) was then intro-duced, these averaging 5 millimeters in length. One small vug inthis seam was filled with chalcedony. Some specimens show datolite resting on coarse granular bluishcalcite which is apparently older than the datolite. Most of thecalcite crystals are, however, distinctly younger and rest upon the ART. 28 MINERALOGY OF TRIASSIC LIMESTONE SHANNON 29 datolite. The first and simplest type of these forms transparent paleamber dog-tooth crystals resting thickly upon free surfaces ofsmall white datolite crystals. These average 4 mm. in length andhave the habit shown in figure 7. Those which were measured gavethe following forms and angles: 3Ieasuremetits of calcite from Leesburg, Figure 7 Form Symbol Quality description Measured Calculated No. Letter Qdt. MiUer « « P 1 -A g +1 +52+61 1121 5271 6171 o / 30 00 30 00 15 32 7 45 44 3166 20 75 35 76 2
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
