Dolomite (Specimen #100263)

Mineral(s): Dolomite, Pyrite 

Location: Helen-MacLeod Mine, McMurray and Chabanel Townships, Algoma District, Ontario  

Size: 8.0 x 6.2 x 2.9 cm 

Description:  A plate of pearly grey dolomite ‘saddles’. The crystals are shiny and some have a light appearance due to very small pyrite crystals sprinkled over the crystal surfaces. The specimen is in very good condition. Specimens like this are rare and from a locality that has been long closed to collecting.

The iron deposits north of Wawa lake were discovered during the Michipicoten gold rush of the late 1890s. The first mine to come into production was the Helen Mine in 1897. Goethite was the principal ore body until [it] exhausted in 1918. Attention in 1939 was then directed to mining siderite ore. The Helen Mine remained an open pit operation until 1950 and in 1960 the George W. MacLeod Mine went into production next to the Helen Mine. Specimens came from both mines, and it is very difficult to distinguish locale – so specimens are labelled as the Helen-MacLeod Mine. The MacLeod Mine closed in December of 1997 as Algoma Steel announced that they could no longer support the high cost of extracting low-grade iron from Algoma Ore.