State by State
- Specimen Number
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."
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
Northern part of Delaware is underlain by hard, Appalachian rocks.
This is an example of a rock that would never have been located without the assistance of a state survey.