AP18 Rhodochrosite

Cannon Mine, Stambaugh, Iron Co., Michigan, USA

7.0x 5.9x 3.6 cm

$450

So by the standards of worldwide rhodochrosite, this piece leaves something to be desired. What makes this piece stand out however, is that it comes from Michigan, and it is particularly rich for the state.

Michigan is best known by mineral collectors for its coppers, however the state was an important iron producer as well.  In 1844 significant iron ore  formations were discovered, and by 1890, Michigan was responsible for 80% of US iron ore production.  This particular orebody was worked later on, from 1910 to 1963.

It is interesting to note the matrix is actually rich iron ore-- it is colored red by iron oxides, and has diffuse gray bands of other minerals (presumably hematite) running through it.

Rhodochrosite is not an iron mineral, but this site produced a number of manganese minerals in addition to the iron ore- shigaite, manganite, and hausmanite to name a few.

This specimen is undoubtedly the result of collecting post-mining, however it remains a rare (and pretty good) example from a classic and historically important US mining district.