Breccia pipe

A breccia pipe, also referred to as a chimney, is a mass of breccia (rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix), often in an irregular and cylindrical shape.

These formations are often hosts for ore deposition especially in copper and uranium mining districts.

[3] Although the origin of breccia pipes is disputed, the most commonly accepted theory is that they formed at intersections of fractures.

However, there are some breccia pipes that are a result of limestone collapse by acidic water or other soluble rock types.

[2][3][4] Areas that contains many examples of breccia pipes include Copper Creek, Arizona, which contains approximately 500 mineralized breccia pipes,[5] and the gold mining area of Cripple Creek, Colorado which contains breccia pipe ore deposits associated with a volcanic diatreme.