- Photomicrograph of thin section of agate/quartz crystal. Agate is a type of quartz found in a variety of rock but characteristically associated with volcanic rock. Due to the way in which they were formed, agate rock often displays either an regimented banding pattern - formed from the layers of siliceous deposits, or a fluid pattern formed from water containing silica and filling cavities within the molten mass. Agate is often used in ornamental items but due to its hardness and resistance to acid it has also been used historically to make pestles and mortars to crush and mix chemicals. Vibrant colours result from imaging with crossed polars.
- Sept 2010
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- Spike Walker, Wellcome Images
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