- Merak (stars.astro.illinois.edu)
MERAK (Beta Ursae Majoris). High in the sky in northern spring evenings, just climbing above the northern horizon in southern hemisphere autumn, the Big Dipper – the “plough” in England – is among the most recognized and recognizable of figures, one of the first learned in a quest to know the constellations.
- 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).