Actinolite

specimen number:
2102176

location:
Sales Creek, Lake Wenatchee, Washington, USA

description:
Good example for the species with lustrous green prismatic crystals of actinolite across the top of matrix. Classic locality for the species.

The Lake Wenatchee actinolite locality, situated in Chelan County, Washington, is a notable site for high-quality metamorphic mineral specimens. Geologically, the actinolite is hosted within the Chiwaukum Schist, a Mesozoic-aged metamorphic unit that underwent intense regional metamorphism. The minerals formed as part of an amphibolite-facies assemblage where magnesium-rich and iron-rich sediments were transformed into lustrous, dark green to emerald-green acicular crystals. These actinolite crystals are often found embedded in a contrasting silvery talc or chlorite schist matrix, sometimes appearing as radiating sprays or "suns." Historically, the site has never been a commercial industrial mine, but it gained popularity among mineralogists and amateur collectors during the mid to late 20th century. While access is governed by its location within the Wenatchee National Forest, it remains a significant reference locality for the study of Cascades metamorphic petrology and is prized for producing some of the most aesthetic actinolite specimens in the Pacific Northwest.

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