Calcite crystals of microbial origin
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Calcite crystals of microbial origin

by Henrik Drake

The photo features calcite crystals precipitated in response to microbial activity (methane oxidation) deep within the Earth's crust - in fractured granitic rock in Sweden. These crystals (about 5 mm in height) act to provide an archive for tracking ancient microbial activity. The tweezers are included for scale.