Spectrum Normalized Raman spectrum of $CaSO_4$ anhydrite acquired with a 514 nm laser Spectrum Normalized Raman spectrum of $CaSO_4 \bullet 2(H_20)$ gypsum acquired with a 514 nm laser Spectrum Normalized Raman spectrum of $CaSO_4 \bullet 2(H_20)$ gypsum in the OH range acquired with a 514 nm laser Spectrum Normalized Raman spectrum of $BaSO_4$ barite acquired with a 514 nm laser Spectrum Normalized Raman spectrum of $PbSO_4$ anglesite acquired with a 514 nm laser