State by State


  • Specimen Number


  • 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

Click here for an explanation of categories and illustrations

Specimen stone for Missouri. Closeup of Missouri
Outline of Missouri width= Geo Map of Missouri.