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.
When this liquid lava gets cooled, it solidifies and gets converted into igneous rocks. Intrusive and extrusive are two types of these igneous rocks. It is the difference between intrusive and extrusive rocks that creates confusion in the minds of students.