• Specimen Number

  5

• Description

  Cut and polished block of dimension stone composed of coarse-grained pink granite.  State survey staff identifies this as Pikes Peak granite, a syenogogranite composed of pink microcline, quartz, hornblende, and biotite.

• Classifications

  Igneous. Plutonic. Granitic. Syenogranite.

• Location & Occurrence

  Potassic pluton from anorogenic Pikes Peak batholith, almost certainly the Pikes Peak Formation. The coarse grain texture and uniformity indicate slow stable cooling at significant depth.

• Geologic Age

  Proterozoic, ~ 1 billion  years old (Ga).

• Geoheritage

  Highest peak in the Mountain State.  Massive granite batholiths float high in the crust, especially after Cenozoic de-lamination of lithosphere.  Being deeply rooted and low-density, they float high. Closeup shows classic granitic texture.

• Links

  USGS Compilation: Search for Colorado in upper right.  Link to State Geological Survey.

• Other

  Credit State Survey.

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