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:
In general, if the semen is still wet it may well have live sperm. As long as freezing conditions remain at a constant temperature, sperm can survive the freezing process indefinitely. Those sperm that die do so within the first 48 hours of freezing, and the attrition rate thereafter is very slight.Frozen semen can be stored for as long as 50 years without additional sperm deterioration beyond that caused by the original freezing process. â¥happily marriedâ¥ Â· 8 years ago.hose sperm that die do so within the first 48 hours of freezing, and the attrition rate thereafter is very slight. Frozen semen can be stored for as long as 50 years without additional sperm deterioration beyond that caused by the original freezing process. â¥happily marriedâ¥ Â· 8 years ago.