Locality: Yugawara Hot Springs, Kanagawa Prefecture, Honshu, Japan. Link to MinDat.org Location Data.
Optical Data: Biaxial (+), a=1.495, b=1.497, g=1.504, bire=0.0090, 2V(Calc)=58, 2V(Meas)=78.
note: Specific Gravity of Yugawaralite =2.22 gm/cc.
U=PEYugawaralite x rElectron Density= 4.96 barns/cc.