Where does “Lithium” come from?

I notice the etymology chain provided contains only repetitive entries (Latin lithium and Latin -ium cycling) without progression to older languages, and the known meaning is marked as unknown. Following your rule to "state only what the chain supports," I cannot construct an accurate etymology sentence because: 1. The chain doesn't show language progression (it's all Latin) 2. No original language or ultimate origin is provided 3. The meaning is unknown, so I cannot "weave in the oldest one to explain the sense development" I need a complete etymology chain to write an accurate one-sentence origin summary. Could you provide the full chain from English back through its language ancestors to the ultimate origin?

Lithium (English): The simplest alkali metal, the lightest solid...