Kidwellite with Strengite
specimen number:
2063580
location:
Three Oaks Gap Mine, Polk Co., Arkansas, USA
description: Located in Polk County, Arkansas, the Three Oaks Gap Mine is a classic Ouachita Mountains mineral locality developed in Paleozoic novaculite and dark shale formations that were subjected to intense regional folding and hydrothermal alteration. Commercial activity at the site was historically focused on manganese and iron extraction during the early to middle twentieth century, exposing oxidized brecciated zones enriched in phosphate minerals. Late-stage secondary weathering within these fracture zones gave rise to rare hydrated iron phosphate species, most notably kidwellite, which was first described from this general region. Kidwellite occurs as striking greenish-yellow, dark green, or brownish silky spherical aggregates, botryoidal crusts, and delicate fibrous tufts lining micro-cavities in the host rock. Although active mining has long ceased and field collecting is limited on public and private lands, the locality remains historical in mineralogy as a co-type locality for kidwellite and a favorite source of micro-specimens for phosphate collectors.
Yellowish green botryoidal crystallized kidwellite covering the top of this matrix. Scattered throughout, quite richly, or purple micro crystal groupings of strengite. Neat combination piece in very good condition. The specimen comes with two previous collection labels, one from that of Ray DeMark, and the other from the mineral's namesake, Al Kidwell.
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