What mineral resource forms only when hot water flows through cracks in rocks? pearls

quartz

halite

amber

Explain how the density of ocean water is affected by temperature and how this results in major ocean currents distributing heat away from the equator toward the poles?

Which revelation resulted from the observation of the spectrum of different galaxies? a. there were more galaxies whose spectrum was blueshifted b. there were no galaxies whose spectrum was redshifted c. there were more galaxies whose spectrum was redshifted d. there were no galaxies whose spectrum was blueshifted

What was apartheid and how did it restrict the rights of non-whites?