Uranophane Pseudomorphic Uraninite & Gummite — Bisundi Pegmatite, Bhilwara District, Ajmer Division, Rajasthan, India

Ex. Collection of Dr. Richard V. Gaines; Ex. Collection of Eric Quinter This specimen is a mineralogical document: a three-stage uranium alteration sequence preserved in place within a single piece from a notable Indian pegmatite locality, carrying double-provenance from two named collections that add both historical depth and scientific authority. The Bisundi Pegmatite is situated within the mica-rich Precambrian pegmatite belt of Bhilwara District, Ajmer Division, Rajasthan — a region intruded by granitic pegmatites into the ancient Aravalli schist terrain during orogenic events of Archaean to Proterozoic age. Fission track geochronological work on pegmatitic minerals from the Bhilwara and Ajmer districts of Rajasthan places the uranium mineralization within the framework of the Delhi Orogenic Cycle, one of the major Precambrian tectonothermal events to affect the region. These pegmatites are uranium-bearing, with primary uraninite occurring as a high-temperature crystallization product within the granite pegmatite system — the same geological environment responsible for well-crystallized uraninite in classic collecting localities worldwide. What distinguishes this specimen is not the primary uraninite in isolation but the complete alteration sequence that developed from it. Gummite is not a single mineral but a descriptive term for the intermediate assemblage of hydrated uranium oxides — principally fourmarierite, vandendriesscheite, becquerelite, curite, and related phases — that form as uraninite begins to oxidize in the presence of meteoric water. The alteration sequence on this piece follows the textbook pegmatite pattern: a central core of black to brownish-black primary uraninite, surrounded by a zone of yellow to orange-red gummite representing the hydrated oxide stage, followed by an outer zone of bright yellow uranophane where the oxidized uranium reacted with silica-bearing waters to produce the calcium uranyl silicate. Each band is a geochemical chapter: the black core records original magmatic crystallization; the orange-red gummite records in-situ oxidation and lead accumulation from radioactive decay; the yellow uranophane rim records final interaction with external siliceous fluids. The result is a visually striking piece — a natural colour gradient from black through orange-red to lemon-yellow — that is simultaneously a complete geochemical record of uranium mobility in a pegmatite system. The first provenance is exceptional. Dr. Richard Venable Gaines (1917–1994) was a mineralogist and economic geologist who trained as an engineer of mines at the Colorado School of Mines and received his doctorate from Harvard University. He is best known as the principal author and lead editor of Dana's New Mineralogy: The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana (8th edition, Wiley-Interscience, 1997) — the definitive single-volume descriptive mineralogy reference covering over 3,700 recognized mineral species, a work still regarded as the authoritative benchmark of the field. Gaines also published original mineralogical research across several decades, including the description of new mineral species, and worked professionally as an economic geologist with Cabot Minerals and other organizations. A specimen from his personal collection carries the implicit vetting of someone who spent a career at the highest level of the discipline. The piece subsequently passed to Eric Quinter, a well-regarded figure in the New York mineral collecting community, before reaching the present. Old collection pieces from named mineralogists of Gaines's calibre are not routinely encountered in the market. Indian pegmatite uranium mineral specimens with this depth of documented pedigree are rarer still. Offered with full provenance documentation as received. Strongly radioactive. Canada domestic shipping only. Approx. specimen size: 25mm x 15mm x 10mm Approx. specimen weight: 13.12 grams (Includes weight of perky box) Approx. specimen activity on an SE International Ranger EXP: 47000 CPM