A mineral which occurs as small colourless plates and typically forms an oxidized crust on arsenical deposits.
Röntgenite is a hydrated acid arsenate of magnesium, MgHAsO4.7H2O. Crystal system: monoclinic..
Origin
Mid 19th century; earliest use found in American Journal of Science. From the name of Carl Rössler, 19th-cent. German scientist + -ite, after German Rösslerit.