Composition: Silver arsenic sulfide
Nomenclature: Named after J.L. Proust, a French chemist.
Industrial Uses: Silver ore.
Additional Notes: Also referred to as ruby silver ore and light red silver ore.
Germany, DDR : Scott 798 : 20 pfennige : 11 Nov 1965
Germany, DDR : Scott 1359 : 50 pfennige : 22 Feb 1972