Entry No. 69 — the Fort Collins file — filed under: historic
Blue Jay Mine
Dating back to the early 1900s, the Blue Jay Mine was once one of Boulder County's most significant producers of fluorspar. Boulder County acquired the 41-acre property in 2000 to preserve its historic surface features, which include a landmarked hoist house, headframe, and ore bin. Today, the structures are fenced off to protect a large maternity colony of bats, but they remain highly visible from the public trail.
The story
In the early 1900s, Jamestown was driven by what came out of the earth, and the Blue Jay Mine was one of Boulder County's most significant producers of fluorspar. For decades, workers hoisted tons of the industrial mineral out of the hard rock, leaving behind heavy wooden infrastructure built to endure mountain winters. By 2000, Boulder County stepped in to acquire the 41-acre property, preserving the site's industrial skeleton before time or weather could knock it down.
What remains today is a remarkably intact triad of mining history: a landmarked hoist house, a timber headframe standing against the sky, and a towering ore bin. But the human workforce has been replaced. Underground, the quiet, climate-controlled mine shafts now host a large maternity colony of bats. Up top, the ground beneath your boots still gives away the mine's original quarry—scattered fragments of raw, vivid purple fluorite lie half-buried along the dirt path.
What it's like
You’ll take a short hike through the Boulder County Open Space trail to reach the 41-acre site. Don't expect to wander inside the buildings: a tall safety fence encircles the entire complex to protect the bat nursery and keep hikers away from unstable historic structures. You get a clear, unobstructed view of the headframe, hoist house, and ore bin from the perimeter, so bring binoculars if you want a closer look at the historic timber joinery. Keep your eyes on the trail dirt for pops of deep purple fluorite as you walk.
The move: Hike the scenic Blue Jay Mine Open Space trail together to view the historic, landmarked mining structures from behind the safety fence, keeping an eye out for fragments of purple fluorite on the ground.
📍 Before you go The mine is located within Boulder County Open Space and is accessible via a public trail, but the historic buildings are fenced off and closed to the public to protect a sensitive bat maternity colony and ensure visitor safety.
- 📍 Jamestown
- 💸 Free
- ⚡ Low-key
- 🌗 Outdoors
Where: Jamestown, CO 80455, USA
Hours: Added 2026-07-20 — confirm current access before you go.
Pair it with
- Lyons Classic Pinball — Head down the canyon into Lyons to trade quiet 1900s mine ruins for the mechanical clatter of over 70 vintage pinball machines.
- Homestead Meadows Trailhead — Double down on Front Range history by hiking to a ghost-town assemblage of late 19th-century ranching and logging cabins.
- The Birch Ruins — Follow up industrial fluorspar ruins with the stone fireplace remnants of a 1900s mountain bungalow perched on a rocky knob in nearby Estes Park.
Good to know
Can you go inside the historic mine buildings?
No. The hoist house, headframe, and ore bin are enclosed behind a security fence to protect a sensitive bat maternity colony and keep visitors safe from structural hazards.
What features are visible from the trail?
You can view the preserved wooden headframe, hoist house, and ore bin, along with remnants of the original surface operation.
What should I look for on the ground?
Watch the dirt along the public trail for small, unrefined fragments of purple fluorspar (fluorite) left over from the mining era.
Where is the mine located?
The site sits within a 41-acre parcel of Boulder County Open Space in Jamestown, Colorado.
Plan a visit & invite your people →
Further reading: bouldercounty.gov · Reddit
last checked: 2026-07-20