Spurrite

specimen number:
2282008

location:
South Peak, Luna Co., New Mexico

description:
A good rich massive example for this mineral.

The South Peak mining area, situated within the Tres Hermanas Mountains of Luna County, New Mexico, is an historic lead-zinc-copper locality characterized by an intricate contact metamorphic mineral assembly. Geologically, the deposit was formed during the Tertiary period when a quartz monzonite stock intruded Paleozoic carbonate rocks, specifically Mississippian Escabrosa Limestone. This intrusion created extensive skarn and calc-silicate hornfels zones, where primary sulfide mineralization underwent heavy supergene alteration to form a diverse suite of secondary minerals, including notable zinc silicates and carbonates like willemite, smithsonite, and calamine. Prospecting and small-scale mining at South Peak began in the early 1900s following the initial discovery of rich lead-zinc veins in the district around 1905. Active extraction peaked during the 1910s and 1920s, with operations gradually tapering off into sporadic, small-scale exploration and specimen reclamation by the mid-twentieth century.

Spurrite is a complex silicate-carbonate mineral that crystallizes in the monoclinic system and serves as a classic indicator of high-temperature, low-pressure contact metamorphism. Geologically, it forms almost exclusively in the innermost contact aureoles of limestone or dolomite formations that have been directly intruded by basic or alkaline magmas, a specialized metamorphic setting known as the sanidinite facies. The mineral typically occurs as dense, massive aggregates, granular groupings, or tabular crystals that range in color from white and gray to light blue, purple, or pale yellow, often exhibiting a vitreous to resinous luster.

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