  fissure vein deposits:http://books.google.com/books?hl=en&lr;=&id;=D_1IlUH-PSIC&oi;=fnd&pg;=PA189&dq;=temperature+sierra+madre+occidental&ots;=0ouOPfiikL&sig;=ztBORaU2_mzjUq5LTMwawLlM4G8#v=onepage&q;&f;=false   