Pyroclastic rocks are the product of explosive volcanism. They are often felsic (high in silica). Pyroclastic rocks are often the result of volcanic debris, such as ash, bombs and tephra, and other volcanic ejecta.henocrysts are crystals that are larger than the matrix and are identifiable with the unaided eye. Rhomb porphyry is an example with large rhomb shaped phenocrysts embedded in a very fine grained matrix. Volcanic rocks often have a vesicular texture caused by voids left by volatiles trapped in the molten lava.
July 9, 2014. Frozen sperm must be stored in extremely cold temperatures (-196 F), but in order to ensure that the fewest possible sperm are damaged, the freezing must be gradual. Generally, the following procedure is followed:
Depending on different situations, sperms can survive from hours to 7 days inside a female's body. When a man ejaculates inside a woman, very few sperms survive long enough to make an attempt at fertilization.In order to do this, they have to get as far as they can in the cervix.evertheless, sperm can only survive for about 20 minutes to an hour depending on its level of exposure to the air and environmental factors. After ejaculation, semen dries up, rendering the sperm useless.