• Specimen Number

  29

• Description

  Weathered boulder of pervasively altered granite with an rusted rim (cortex).  Identified by the Missouri Survey as the Slabtown Granite, described by the USGS, a "fine-grained granite, usually porphyritic, mottled pink and green (mafic minerals)... Weathers to dull buff to brown, blocky, tabular cobbles." This description matches our sample.

• Classification

  Igneous. Plutonic. Granitic. Granite.

• Location & Occurrence

  Slabtown Granite Formation occurs in the St. Francois mountains in the southeastern part of the state. From the map, the southeastern part of the state is most highly deformed and faulted.

• Geological Age

  Precambrian. Proterozoic, with a Rb-Sr age of ~1300-1400 Ma.

• Geoheritage

  Ancient rock from an otherwise inconspicuous orogen.

• Links

  Link to State Geological Map from USGS.  Link to Missouri Geological Survey.  Link to USGS Description of Slabtown Granite.

• Other

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