  First geometric calculus alongside its description of equiangular spirals,
reflections and rotations is introduced briefly. Then single and double
reflections at such a spiral are investigated. It proves suitable to
distinguish incidence from the \textit{right} and \textit{left} relative to the
radial direction. The properties of geometric light propagation inside the
equiangular spiral are discussed, as well as escape conditions and
characteristics. Finally the dependence of right and left incidence from the
source locations are examined, revealing a well defined inner \textit{critical}
curve, which delimits the area of purely right incident propagation. This
critical curve is self similar to the original equiangular spiral.

Optics