Rockbridgeite - (Iron Manganese Phosphate Hydroxide) - Color is brown, dark green, yellow-brown or black.
Goethite - (Hydrated Iron Oxide) - Color is yellow, brown, brownish red to black. Sometimes tarnished with irridescent colors.
Strengite - (Hydrated Iron Phosphate) - Color is colorless or white, but more commonly pink to violet red.
"Rockbridgeite is named after the type locality at the Midvale Mine, South Mountain, Midvale, Rockbridge Co., Virginia."
ROCKS AND MINERALS - January/February 1989 Vol.64