Aegirine

specimen number:
2062259

location:
Wausau, Marathon Co., Wisconsin, USA

description:
A set of two matrix specimens with radiating crystals of aegirine throughout matrix. Interesting locality example for the species. Size is provided for the larger of the two examples

The Wausau pluton, located near Wausau in Marathon County, Wisconsin, represents a major crystalline rock complex that has been extensively quarried for industrial dimension stone and crushed aggregate. Geologically, the pluton is a classic example of a Paleoproterozoic-age anorogenic intrusive complex, forming part of the broader 1.5-billion-year-old Wolf River Magmatic Event, where rising alkaline magmas cooled slowly deep within the Earth's crust. This tectonic setting produced a highly variable suite of coarse-grained igneous rocks, including syenite, quartz syenite, nepheline syenite, and distinct red granites composed primarily of potassium feldspar, amphibole, and quartz, with localized pegmatite pockets containing unusual accessory minerals. Historically, commercial quarrying within the Wausau pluton began during the late nineteenth century around 1880, expanding rapidly in the early twentieth century as the region became famous for producing a durable, highly uniform deep-red dimension stone commercially marketed as Rib Mountain Red or Wausau Red Granite. Numerous large-scale quarries operated continuously across the pluton throughout the mid-to-late twentieth century to supply architectural stone for major buildings across the United States, and while dimension stone extraction has scaled back, several modern operations remain actively focused on producing industrial crushed stone and roofing granules.

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