File:Spokane Sapphire Mine (near Helena, Montana, USA) 8.jpg

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English: On the southern side of the Missouri River near Helena, Montana is the Spokane Sapphire Mine, a fee site at which pale-colored sapphires can be collected. They are derived from a Pleistocene-aged river terrace gravel deposit. The mine removes the largest clasts (cobbles), washes the ultrafines away, and provides the processed gravel to visitors. Sapphires and other heavy minerals (e.g., pyrite and garnet), plus occasional fossils, can be collected from density concentrates.

Sapphire is a gem-quality variety of corundum, Al2O3 (aluminum oxide). The common color of sapphires from here is extremely pale blue. The provenance may be sapphire-bearing, vesicular, porphyritic andesite dikes.

Seen here is a pile of processed gravel. The raw gravel is very poorly sorted.

Locality: Spokane Gravel Bar, southern slopes of the Missouri River Valley, northeast of the town of Helena, southeastern Lewis and Clark County, western Montana, USA (46° 39’ 40.74” North latitude, 111° 48’ 37.49” West longitude)
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Source https://www.flickr.com/photos/47445767@N05/51357182594/
Author James St. John

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This file is licensed under the Creative Commons Attribution 2.0 Generic license.
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/51357182594. It was reviewed on 6 August 2021 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0.

6 August 2021

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current16:10, 6 August 2021Thumbnail for version as of 16:10, 6 August 20213,008 × 1,594 (4.1 MB)Ser Amantio di Nicolao (talk | contribs)Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/51357182594/ with UploadWizard

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