Historic French Gulch Quartzite (cc1-1)

Iron-stained Goethite Quartzite & The Reiling Dredge

A PLACER GOLD LEGACY

In the late 19th and early 20th centuries, gold mining in French Gulch, near Breckenridge in Summit County, Colorado, shifted from hard rock to large-scale placer operations.

One of the most notable methods used was the Reiling Dredge, a floating mechanical gold dredge designed to process thousands of yards of rock per day. This massive machine scooped up streambed sediments and processed them onboard, separating heavier gold from lighter waste rock using sluices and riffles.

The dredge slowly moved through the gulch, leaving behind tailings containing a geological signature of the region’s rich mineral history.

Miners have identified iron-stained goethite quartzite—a hallmark of weathered gossans, which are rusty, oxidized cappings above sulfide-rich ore bodies. The gossans in French Gulch marked the upper reaches of veins that had once held valuable gold, silver, and other metals.

The orange-red staining came from the goethite, an iron oxide mineral, forming when pyrite and other sulfides oxidized near the surface. These colorful indicators often led prospectors to richer underground ore bodies and reflect the enduring legacy of French Gulch’s metallogenic wealth.

These mining tailings are intended for our walk-in store, but also available for purchase online. Sold assorted, Price is for one. rock