For example, the minerals baddeleyitean oxide of zirconium ZrO 2and zirconolite CaZrTi 2 O 7have been shown to be widespread in small amounts in mafic igneous rocks i. For some other materials, the event is the end of a metamorphic heating event in which the rock gets baked underground at generally over a thousand degrees Fahrenheitthe uncovering of a surface by the scraping action of a glacier, the chipping of a meteorite off of an asteroid, or the length of time a plant or animal has been dead. Carbon is also passed onto the animals that eat those plants. Younger rock is not found in number of meteorites.
Thus, grains with a diameter comparable to that of a human hair, selected under a microscope to be crack-free and of the highest possible quality, have been found to be more concordant than cracked grains.