Thallium

Thallium was discovered through spectroscopy, distinguishing itself with a bright green spectral line. This element, derived from heated selenium ores, was significant for its unique identifying characteristic via spectroscopy.
 William Crookes England 1861 Thallium

Thallium was discovered through spectroscopy, distinguishing itself with a bright green spectral line. This element, derived from heated selenium ores, was significant for its unique identifying characteristic via spectroscopy.