Minerva Mine (Minerva No. 1 Mine)

The Minerva No. 1 Mine, north of Cave-in-Rock in Hardin County, Illinois, was the largest fluorspar orebody in the historic Cave-in-Rock mining sub-district — and one of the best mineral specimen producers in Illinois history. Beyond fluorite, it turned out exceptional witherite, alstonite, benstonite, and strontianite, including the famous "Blue Cap Pocket" find of September 1990, a one-time combination collectors still talk about. Ozark-Mahoning shut the mine down for good on the last day of January 1996; the shafts have since been filled, buildings removed, and the ground reclaimed to open gravel fields and small hills. It's private land now, owned by a local mining company, with posted no-trespassing signs — real history behind this listing, but not a site to walk onto without checking first.

The former mine site is north of the town of Cave-in-Rock, Hardin County, Illinois, along the Ohio River in the Cave-in-Rock fluorspar mining sub-district.

Not applicable as an active dig — the mine is closed and reclaimed. Any historical collecting happened underground or on mine dumps that no longer exist in their original form; today's ground is graded gravel fields on private property.

The site is privately owned, reportedly by a local mining company (Hastie Mining Co., per collector sources), with "private property" signs posted. Some local accounts suggest the owner has informally tolerated rockhounds picking through the reclaimed gravel fields since the shafts were filled and buildings removed, but this conflicts directly with the posted signage — treat it as permission-required and contact the landowner before visiting rather than relying on secondhand tolerance claims.