Can't download audible books to MP3 player - not happy, Jan. So I sprang the 50 bucks to buy a generic Dick Smith MP3 player because I thought - oh joy - I'd be able to carry my entire audible library around with me on a device that's as small as a matchbox. So I download some audible books. They're there on the device.
A common example of an extrusive igneous rock is basalt. Some extrusive rocks, such as obsidian and pumice, cool so rapidly that they completely lack crystal structure and are considered a volcanic glass. Pumice is just like obsidian except it is tiny shards of glass.
None of these have pores usually. But when the magma erupts as in a volcanoe, and if the volcanoe also contains lots of gass then you get very porous igneous rocks, such as vascular basalt, right through to pumice, whick is a glassy sponge, so light it floats on water.ll down to the formation of the rock types. Igneous are created by the cooling of magma, either within the earth itself (Intrusive) or as it erupts out of the ground (Extrusive). This cools to form vaious hard rocks such as Granite.