Deer Lake peridotite (completely serpentinized)

Cllick on image to enlarge.          Photo © Daniel R. Snyder

The Deer Lake peridotite crops out in a small area north of Ishpeming, in Marquette County, northern Michigan. Although the geologic map of the area labels this exposure as "peridotite" (according to convention), because if its inferred protolith  it is in fact serpentinite. Pictured are two varieties of serpentine, as well as magnetite (black lines and spots) and hematite (reddish-brown areas) from the original olivine and pyroxene, which couldn't be taken up by the serpentine. The magnetite makes this rock weakly magnetic. XPL. Imaged area 1.3 mm x 2 mm. Link to photo of hand samples