Spokane Bar Sapphire Mine

Useful Information

Location: Northeast of Helena. Take York Road to Mile Marker 8, turn right on Hart Lane, after road makes 90 degree turn left on Castles Road.
Open: APR to OCT daily 9-17. [2006]
Classification: Sapphire Mine
Guided tours:
Address: Spokane Bar Sapphire Mine and Gold Fever Rock Shop, 5360 Castles Drive, Helena, MT 59602, Tel: +1-406-227-8989, Fax: +1-406-227-8989, Toll Free: +1-877-DIGGEMS (344-4367). E-mail: contact
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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The geologic structure called Spokane Gravel Bar is a deposit consisting of unsolified sediments, deposited by an ancient river. It is located near Hauser Lake along the Missouri River. Discovered in the early 20th century by geologists mapping the Missouri River area, it was named after the Spokane Hills which are composed of Spokane shale. The present river level is more than 50 m below the ancient river deposits. Four major gravel terraces are visible on both sides of the river.

Gravel bars are important sites for placer mining, the gravel is a product of erosion and typically resistant metals and minerals, who resist the erosion, are accummulated by this process. Placers are the classic gold rush deposits, as gold is very commonlly found in such placers. It is inert and not altered by erosional processes.

In this case there was only little gold but sapphires. This gemstones are very hard and resistant against many erosional processes. Like the gold they were not destroyed, but accumulated.


Spokane Bar Sapphire Mine is a sort of public rock collecting area, not a deep mine. Originally the gravel was mined by gold diggers in the clasic way, they constructed a canal and used the water power to wash away the gravel into wooden sluice boxes. This boxes were built to catch the heavier part of the gravel. They tried to wash gold, but instead they found heavy and hard rocks, they did not know. The puzzled miners sent samples to England where they were identified as sapphires and termed valueless.

Today the Spokane Bar Sapphire Mine is half a mining museum, showing the remains of the old mines, and half it is a paradise for mineral collectors. Sapphires in every color can be found, most common are the green-blue ones. Blue sapphires are the best known but Ruby, red sapphire, is the most valuable. They are easy to recognize by their hexagonal crystal structure with triangle terminations, which are often flat.

The mine also contains many other gemstnes and minerals, including diamonds, topaz, and citrine.