Definition: Oculus, Perfect Number, Rotunda, Scoria, Porphyry, Groundmass, Aphanitic

THE PERFECT number… and some architectural features found in the Pantheon.

 

Oculus

A round or eye-like opening or design

 

Perfect number

A whole number whose summed factors equal it (6,28,496,8128)

 

Rotunda

Any building with a circular ground plan, and sometimes covered by a dome

 

Scoria

A low-density, lightweight volcanic rock

 

Groundmass

The compact, finer-grained material in which the crystals are embedded in a porphyritic rock (groundmass also called matrix)

 

Aphanitic

Fine grained

 

Porphyry

An igneous rock consisting of large-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate rich, generally aphanitic matrix or groundmass