Lydium
/ˈlɪdiəm/noun
A dark, fine-grained stone formerly used as a touchstone for testing the purity of gold and silver.
Did you know?The touchstone’s power was practical rather than magical: rubbing precious metal against it left a streak whose color could be compared with known samples to judge purity.
Etymological Timeline
Ancient Greek
Greek
Λυδία (Lydía)
“Lydia, the region of western Anatolia associated with early gold and silver refining”
Classical Greek
Greek
Λύδιος (Lýdios)
“Lydian; of or from Lydia”
Classical Latin
Latin
lydius
“Lydian, especially a Lydian stone used to test metals”
Late Latin
Latin
lydium
“A Lydian touchstone; the neuter form used as a noun”
17th Century
English
lydium
“A dark stone used as a touchstone for determining the quality of precious metals”
Modern English
English
lydium
“A chiefly historical or technical term for a touchstone”