The Collaborative International Dictionary of English v.0.48:

Goa powder \Go"a pow"der\ [So called from Goa, on the Malabar
   coast, whither it was shipped from Portugal.]
   A bitter powder (also called araroba) found in the
   interspaces of the wood of a Brazilian tree (Andira
   araroba) and used as a medicine. It is the material from
   which chrysarobin is obtained.
   [1913 Webster]