A common aphanitic igneous rock formed during the rapid cooling of lava on or near the surface of a planet, basalt has been located on Earth, Mars, Venus, Jupiter’s moon Io, Earth’s Moon and even on the asteroid Vesta. Composed primarily of feldspar in the form of plagioclase, on this planet basalt also contains a high percentage of quartz and silica with traces of magnesium and sodium. Given the youth of this planet, basalt is plentiful and easily quarried, leading to its use for a variety of purposes. Along with its utility as an inexpensive building and paving material, basalt can be heated to high temperatures (at least 1600 degrees C) and extruded, producing “stone wool,” a superior thermal insulator. Colonists also use stone wool for filtration systems, soundproofing, manufacture of plastics and germination of hydroponic seedlings brought from Earth. Although there are some health risks to prolonged exposure to stone wool and precautions should be taken, in general these are slight and far outweighed by its utility.