Calcite

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A grouping of colorless platy rhombohedral calcite crystals, these mostly gemmy and without matrix. Crystallized all around and in good condition. Neat locality example for the species. The specimen comes with a previous label from the collection of Ray DeMark.The Martin-Marietta Mine near Lyons in Boulder County, Colorado, is situated along the eastern foothills of the Rocky Mountains, where regional geology is dominated by the Permian-age Lyons Sandstone and surrounding sedimentary strata. This formation consists primarily of quartzose sandstone featuring well-sorted grains and iron-oxide or silica cement. The area has a long-standing history of industrial mining, transitioning from historic stone quarries that extracted famous local building materials to modern operations focused on producing aggregates, sand, and gravel for regional construction.