Most of the Carrara minerals are in the form of small crystals, which can be difficult for showgoers to fully appreciate; so in order to help show the beauty of the delicate crystals of wurtzite, sphalerite, colusite
, sulvanite, rutile, quartz, tetrahedrite and many other species, excellent photos by Roberto Appiani and Matteo Chinellato were shown in sequence on the large overhead screens above the exhibition area.
Today the Butte mines are closed and flooded, but its mineralogical legacy of fine specimens remains--most noteably the copper sulfide and sulfosalt minerals such as bornite, chalcocite, chalcopyrite, colusite
, covellite, digenite, djurleite, and enargite, and other minerals such as barite, pyrite, quartz and silver.
I gave him two of the specimens for the Anaconda Reference Mineral Collection, and in exchange he gave me my choice from among a dozen or so small colusite
crystals on enargite which had been collected by Bob Ingersol on the 3200 level of the Leonard mine.
In these cavities many other sulfosalts have been found: guettardite, robinsonite, zinkenite, boulangerite, semseyite, jordanite, tetrahedrite, sulvanite, colusite
, famatinite and kesterite.
Specimens of copper sulfides and sulfosalts like bornite, chalcocite, colusite, covellite, digenite, djurleite, and enargite rank among the finest in the world.
It is included in this brief register because it was the major source of the single Butte type-species, the mineral colusite.
In addition to colusite, the East Colusa produced a mineral suite similar to that of the adjacent Leonard mine.
Although they are found in smaller amounts elsewhere, this same area hosted the rare species colusite and betekhtinite, together with most of the high-sulfur copper minerals, covellite, digenite, and djurleite.
The East Colusa and the Leonard, near Meaderville, were producing fantastic crystal groups of enargite, pyrite, covellite, digenite, and colusite
The first species deposited were: quartz (not common here), galena, pyrite, sphalerite, enargite, colusite and fluorite.
A few specimens of colusite crystals up to 4 mm, with typical tetrahedral habit, bronze-yellow color and metallic luster, have been found in the Costa and Pitone quarries.
The red variety is associated with galena, geocronite and bournonite; the yellow variety with colusite, wurtzite and robinsonite.