Icelandite is a very specific sub-variety of andesite, a volcanic rock associated with basalt. Icelandite
has the distinction of being called the "closest thing on Earth to the rocks found at the (Mars)
Pathfinder landing site".
Take a look again at the pictures of Mars taken during the Pathfinder mission...there's Yogi,
Barnacle Bill, Stimpy, Flattop and the whole rocky gang...and they all have chemistry that most
resembles this sample!
Specimen is presented in a 1.25-inch hinged perky.