16 Matching Annotations
  1. Apr 2021
  2. Mar 2021
  3. Feb 2021
  4. Dec 2020
  5. Sep 2020
  6. Jul 2020
  7. Jun 2020
  8. Jan 2020
  9. Jun 2019
    1. Despite their name, rare-earth elements are – with the exception of the radioactive promethium – relatively plentiful in Earth's crust, with cerium being the 25th most abundant element at 68 parts per million, more abundant than copper. However, because of their geochemical properties, rare-earth elements are typically dispersed and not often found concentrated in rare-earth minerals; as a result economically exploitable ore deposits are less common.[4] The first rare-earth mineral discovered (1787) was gadolinite, a mineral composed of cerium, yttrium, iron, silicon, and other elements. This mineral was extracted from a mine in the village of Ytterby in Sweden; four of the rare-earth elements bear names derived from this single location.
    2. The 17 rare-earth elements are cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), and yttrium (Y).
  10. Nov 2018
    1. Jean Prévost’s “La Première Partie des Subtiles et Plaisantes Inventions,” the earliest known important conjuring book, printed in Lyons in 1584.
  11. app.getpocket.com app.getpocket.com
    1. Jean Prévost’s “La Première Partie des Subtiles et Plaisantes Inventions,” the earliest known important conjuring book, printed in Lyons in 1584.
  12. Nov 2017
  13. Feb 2015