To geoscientists, rocks are not nouns but verbs - far more than inert curios, they are evidence of Earth's ebullient creativity, its capacity for ceaseless reincarnation of primordial matter into new forms. Rocks are transcripts of eons of conversation between the solid earth and water, air and life.
Acasta Gneiss Complex, are celebrities: the oldest yet found on Earth, clocking in at the astonishing age of 4.03 billion years.
amethyst: the name given to it by the ancient Greeks, amethustos or "not drunken," which was based on their belief that it allowed the wearer to drink wine without becoming intoxicated.
A useful cultural unit of time is the saeculum–broadly, the time between a major event like a war of an epidemic and the death of the last person who had firsthand memories of it.
Areology is the rather ungainly term for the study of the "geology" of Mars, a modern homage to the ancient Greek warrior god Ares (counterpart to the Romans' Mars.) Since geology literally means "the science of Earth," the term isn't technically correct when applied to other planets or moons. The study of Earth's moon is sometimes called "selenology" for the Greek moon goddess Selene, a term that peaked in popularity in the late 1960s in the lead-up to the Apollo moon landing.
The diggers and grubbers that first appeared in the Cambrian also brought an end to the long reign of Earth's first complex ecosystems - the stromatolites, teeming mats of microbes that had thrived for eons in shallow coastal waters since early Archean time.
Chondrites – or materials with chondritic composition – were thus the universal ancestors of all rocks on Earth, and other rocky planets and moons. They preserve a memory of the starting composition of these worlds, something that all other rocks have forgotten, particularly on Earth, where the process of differentiation has continued for 4.5 billiion years and generated a prodigious diversity of rocks that fall far from the chondritic tree in their chemistry.
