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The agatebearing lava in the Midland Valley Scotland OOLolb
Rocks in thin section equipment and techniques ll
The microstructure of agate
8 other sections not shown
agate genesis alkaline alteration amorphous silica amygdale andesite banding in agate blue-white bands bubbles calcite cavity celadonite centre chalcedony chert clear chalcedony concentration conﬁrm containing cover slip cristobalite crossed polars crystallisation front difﬁculties entered the vesicle feldspars ﬁbres ﬁbrosity ﬁeld ﬁlled ﬁlling ﬁnal ﬁne ﬁrst ﬂat form of silica fortiﬁcation agate grinding grit growth Heddle Heinz hematite horizontally banded agate hydrothermal hypothesis impurities inﬁltration canal ions iron compounds iron oxide lava lava ﬂow layer Liesegang Liesegang Rings magma magniﬁcation micrograph Midland Valley minerals moganite Moxon Nacken Noeggerath nucleation observed opal content outer Path of Condie plane polarised light polariscope polaroid precipitation produce quartz quartz crystals quartz grains rhythmic banding rock samples scientiﬁc Scottish agates Short edge represents silica gel silica glass silica solution silica source silicic acid slide spherulitic stage sufﬁcient suggested surface temperature texture thickness thin section vesicle volcanic white bands yellow