Xonotlite

specimen number:
2354095

location:
Hunting Hill Quarry, Rockville, Montgomery Co., Maryland, USA

description:
Excellent for the species, bright white sprays of acicular xonotlite crystals to 1.5 cm in size scattered richly across one side of matrix. This is in very good condition.

Located in Montgomery County, Maryland, the Hunting Hill Quarry operates within a Serpentinite body embedded in the local metamorphic bedrock of the Appalachian Piedmont. Extensive quarrying for crushed stone exposed a complex network of altered ultramafic rocks cut by hydrothermal veins and rodingite dikes, rich in calcium and magnesium silicate minerals. Hydrothermal alteration within these vein systems favored the formation of xonotlite, a rare calcium silicate mineral that typically occurs as compact fibrous masses or radiating acicular sprays with a distinct white to pale gray color. Mineral collectors highly value Hunting Hill Quarry for its unusually fine specimens of xonotlite, alongside a broad diversity of secondary vein minerals, making it one of Maryland's most famous historic micro-mineral collecting sites prior to the restriction of field access.

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