Pseudomalachite

specimen number:
2133245

location:
Lodi #4 claim, Plumas Co., California, USA

description:
Green botryoidal rich pseudomalachite across the top of matrix. In good condition. Neat locality example for the species, collected by Chuck Trantham.

The Lodi #4 claim, situated in the Genesee District of Plumas County, California, is a specialized mineral locality known for its secondary copper mineralization. Geologically, the deposit is hosted within Paleozoic-aged metamorphic rocks, including greenstone and schist, where primary copper sulfides have undergone oxidation to form a variety of phosphate and carbonate minerals. The site is particularly notable for the occurrence of pseudomalachite, a copper phosphate mineral that typically appears as dark green, botryoidal crusts or radiating fibrous aggregates, often found in association with libethenite and cornwallite. Historically, the Lodi claims were part of a series of small-scale prospecting and mining efforts focused on copper and gold that occurred sporadically from the late 19th century through the mid-20th century. While the Lodi #4 claim never reached the status of a major commercial producer like the larger mines in the nearby Walker Mine district, it remains a site of significant interest to mineralogists for its diverse and well-crystallized secondary copper species.

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