Calcite (O-0011)

specimen number:
9273147

location:
July 4 Pocket, Rodeo, Durango, Mexico

description:
Glassy gemmy colorless twinned crystal grouping of calcite. Complete all around and in excellent condition.

The July pocket, an exceptional mineral-bearing cavity discovered near the town of Rodeo within the Rodeo Municipality of Durango, Mexico, represents a famous localized extraction point celebrated among collectors for producing highly distinctive, sharp specimens of calcite. Geologically, the localized mineralization is hosted within the extensive Tertiary-age volcanic sequences of the Sierra Madre Occidental, where regional tectonic faulting and fissuring created open structural pathways through thick, porphyritic rhyolite flows. Low-temperature, calcium-rich hydrothermal fluids circulating through these open fault zones precipitated highly unusual crystal habits, most notably the pristine, overlapping tabular calcite plates that form intricate boxwork geometries popularly referred to as angel wing calcite. Historically, targeted manual surface trenching and pocket excavation at this site reached a prominent peak during a highly successful specialized recovery effort in July of 2008, when local miners opened a substantial, pristine vug that yielded a finite abundance of clean, undamaged display specimens. Because the pocket was a highly localized geologic anomaly rather than a continuous strata-bound industrial orebody, active manual extraction at the immediate pocket site was short-lived and concluded following the clearance of the primary chamber walls, though small private syndicates continue intermittent regional exploration for similar blind calcite-bearing structures across the rhyolitic terrain through 2026.

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