MUMBAI: Gold prices reacted sharply by Rs 80 per ten gram on the bullion market here today on weak London advices coupled with poor seasonal demand. Silver also fell steeply on subdued overseas advices and good arrivals of raw silver.Standard gold started weak at Rs 4180 and fell further to close at Rs 4155, showing a steep fall of Rs 80 over the last close of Rs 4235. 22-carat gold was nominally quoted lower at Rs 3845 from Rs 3920 and ten-tola gold bar nosedived by Rs 1000 to settle at Rs 48,700 as against the previous close of Rs 49,700. Ready silver of .999 fineness dropped to close at Rs 8640.