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This visually striking 727-gram specimen is a superb example of Pilot Knob breccia, showcasing a chaotic mix of vibrant, deep orange and red rhyolitic jasper fragments. What makes this piece truly special is the matrix holding those fragments together: a dense, dark hydrothermal veining that is slightly magnetic, indicating the presence of Pilot Knob’s famous iron ore (magnetite) naturally cementing the shattered jasper back into a solid block.
The lapidary work on this specimen is uniquely crafted for premium display. It has been meticulously cut and polished into a freestanding 3/4 cone. The front display face features a beautifully rounded, high-gloss polish that highlights the vibrant contrast between the red rhyolite and the black magnetic veins. The base has been cut completely flat for a secure, upright stance, while the back quarter of the stone has been left completely natural and unpolished, allowing you to see and feel the raw, weathered state of the brecciated ore.
Dimensions: 5.75\" tall x 3\" wide x 2.75\" deep
Weight: 727 grams (approx. 1.6 lbs)
Provenance: Pilot Knob, Iron County, Missouri
The History: Pilot Knob Breccia
Located in the St. Francois Mountains, Pilot Knob is a historic Precambrian site famous for massive iron deposits and ancient volcanic activity. Millions of years ago, explosive volcanic forces and tectonic shifting violently shattered (brecciated) beds of rhyolite and jasper. Deep hydrothermal fluids rich in silica and heavy iron then flooded into these shattered cavities. As the fluids cooled, the iron and quartz precipitated out, acting as a natural weld that locked the jagged fragments together forever. This piece perfectly demonstrates that violent geological dir=\"ltr\" style=\"margin-top:0; margin-bottom:0;\">Pilot Knob Missouri, Iron County MO geology, brecciated jasper, rhyolite breccia, magnetic iron ore, magnetite matrix, KeepsCache, polished mineral cone, freestanding display rock, St. Francois mountains, midwest rockhound, lapidary art, hydrothermal breccia, partially polished rough.
