// MATTER · ELEMENT 57 / 118atoms.no/elements
La57
Lanthanum
La·Z 57·Lanthanide·138.9·⭕ 1A · G♯ Minor
▸ The reading
interpretive · artLanthanum is named from the Greek 'lanthano' — to lie hidden — because it spent thirty-six years concealed inside cerium minerals. It then powered carbon-arc cinema light and the NiMH batteries of the first mass hybrids. The hidden one who opens the whole lanthanide procession: the name was the reading all along.
The science below is cited as science; the symbolic layers are flagged as interactive art.
⚜ Periodic Frequency
1AG♯ Minor
a seat struck in brass — testimony, not prediction
the seat has its own room on ⭕ THE OVAL TABLE — tap the code
▸ The lenses
▸ Discovery
Carl Gustaf Mosander — separated 'lanthana' from impure cerium nitrate · Sweden · 1839
▸ Stellar origin
s-process + r-process branchingLanthanum sits at the entry to the rare-earth row. Stable isotopes show both slow- and rapid-neutron-capture fingerprints.
▸ Reactivity
Oxidizes rapidly in moist air; pyrophoric in powderBegins the lanthanide row, where 4f electrons mean nearly identical chemistry across fourteen consecutive elements.
▸ Applications
- Carbon-arc lamp electrodes (vintage cinema)
- Nickel-metal-hydride battery negative electrodes
- Camera lens glass (high refractive index)
- Petroleum cracking catalysts (zeolites)
▸ Curiosity
Hidden among cerium minerals for half a century — the name from Greek 'lanthano,' meaning to lie hidden, which it had been doing.
▸ Related readings
a resonance drawn between readings — not a claim that they share an origin.