• Specimen Number

  7

• Description

  Cut block of dimension stone inscribed with the name "DELAWARE."on a smooth, but not polished, face.  Identified by state survey staff as likely the Brandywine Blue Gneiss, a formation of  "medium to coarse grained granulites and gneisses composed of plagioclase, quartz, orthopyroxene, clinopyroxene, brown-green hornblende, magnetite, and ilmenite."

• Classification

  Metamorphic. Gneiss. Granitic.

• Location & Occurrence

  Located by survey staff as likely from near Brandywine Creek. Our specimen is definitely layered, but not blue, a high-grade, mountain root, dynamothermal, metamorphic rock.

• Geological Age

  Ordovician.

• Geoheritage

  Northern part of Delaware is underlain by hard, Appalachian rocks.

• Links

  USGS Compilation: Search for Delaware in upper right.  Link to State Geological Survey. Link to Unit Obbg at Delaware Survey.

• Other

  This is an example of a rock that would never have been located without the assistance of a state survey.

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