- NGC 457 (Wikipedia)
NGC 457 (also designated Caldwell 13, and known as the Dragonfly Cluster, E.T. Cluster, Owl Cluster, Kachina Doll Cluster or Phi Cassiopeiae Cluster) is an open star cluster in the constellation Cassiopeia.
- Greenschist (Wikipedia)
Greenschists are metamorphic rocks that formed under the lowest temperatures and pressures usually produced by regional metamorphism, typically 300–450 °C (570–840 °F) and 2–10 kilobars (29,000–145,000 psi). Greenschists commonly have an abundance of green minerals such as chlorite, serpentine, and epidote, and platy minerals such as muscovite and platy serpentine. The platiness gives the rock schistosity (a tendency to split into layers). Other common minerals include quartz, orthoclase, talc, carbonate minerals and amphibole (actinolite).