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:
Confidence votes 26. The sperm count is dependent on the temperature of the testes. The testes are external to the body because they require a lower temperature to produce viable sperm. The testes work best at temperatures slightly less than core body temperature.Spermatogenesis is less efficient at lower and higher temperatures.This is the reason for retraction of the testes in the cold as well as non-viable sperm in men with (medically) undescended testes.he testes work best at temperatures slightly less than core body temperature. Spermatogenesis is less efficient at lower and higher temperatures. This is the reason for retraction of the testes in the cold as well as non-viable sperm in men with (medically) undescended testes.