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Analytical chemistry and mineral separation · 1797–1858

Carl Gustaf Mosander

Mosander worked in Stockholm in Berzelius’s circle, first in pharmacy and medicine and then in mineral analysis, and he inherited the problem that the Swedish minerals cerite and gadolinite had handed to the previous generation. His method was fractional treatment carried out with unusual persistence: dissolve, precipitate part of the material under carefully chosen conditions, set the fractions aside, and repeat until the properties of successive fractions stopped drifting. That drift was the evidence. A single earth that behaved slightly differently after each cycle was, to him, a mixture that had not yet been taken apart.

Explore the supporting references at the foot of this article.

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Contribution & context

Between 1839 and 1843 he divided two supposed elements into several. Ceria yielded lanthana, and then a further fraction he called didymia; yttria yielded, alongside yttrium, the fractions he named erbia and terbia. Some of these were themselves mixtures that later workers divided again, and the names were partly swapped in the process, so his announcements are better read as the opening of a long separation program than as four finished discoveries.

afdc.energy.gov — CeriumLANL Periodic Table — LanthanumRSC Periodic Table — LanthanumLANL Periodic Table — Ceriumemsl.pnnl.gov — Cerium

Discoveries in context

Fourteen elements hidden in one mineral ↗

The rare earths were separated from one another over more than a century, because chemically similar elements resist the methods that separate ordinary ones.

Continue the story

Follow a discovery, compare a material choice, or meet the people behind an idea.

DISCOVERY HISTORYFourteen elements hidden in one mineral ↗See how his fractional method became a century-long program carried on by other analysts.SCIENTISTJean Charles Galissard de Marignac ↗Follow the same problem in the hands of a chemist who combined separation with precise atomic-weight work.

Sources & further reading

  1. afdc.energy.gov — Cerium ↗afdc.energy.govReference explanation · Source checked
  2. LANL Periodic Table — Lanthanum ↗Los Alamos National LaboratoryReference explanation · Source checked
  3. RSC Periodic Table — Lanthanum ↗Royal Society of ChemistryReference explanation · Source checked
  4. LANL Periodic Table — Cerium ↗Los Alamos National LaboratoryReference explanation · Source checked
  5. emsl.pnnl.gov — Cerium ↗emsl.pnnl.govReference explanation · Source checked

Sources and further reading. What the review labels mean