Beta tridymite is a silicate formed at approx. 1500C in volcanoes & shares a structural similarity to ice.
Silicates are very common on Earth but the tridymite structure is unusual in that it requires a 5000C temperature to create it. NASA scientists were surprised to find it on Mars as is explained in: NASA Scientists Discover Unexpected Mineral on Mars.
|67304C||Atom, Minit, O, 180 degree, red||111|
|67328C||Atom, Minit, Metal, tetrahedral, grey||70|
|67180-15||Minit bonds 15mm, clear vinyl||222|