Pseudobrookite
Videos
Pseudobrookite is an iron titanium oxide mineral with formula: Fe2TiO5 or 2O5.
Spray of pseudobrookite needles from Topaz Mountain in Utah (size: 2.7 × 2.0 × 1.6 cm)
Rhyolite
Videos
Rhyolite is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained in texture, but may be porphyritic, containing larger mineral crystals in an otherwise fine-grained groundmas
QAPF diagram with rhyolite field highlighted
Rhyolite beach on Lake Superior
Aphanitic rhyolite