%0 Journal Article %J Geological Society of America Bulletin %D 1961 %T KNOOP HARDNESS NUMBERS FOR 127 OPAQUE MINERALS %A ROBERTSON, FORBES %B Geological Society of America Bulletin %V 72 %P 621 %8 Jan-01-1961 %G eng %U https://pubs.geoscienceworld.org/gsabulletin/article/72/4/621-637/5310http://bulletin.geoscienceworld.org/cgi/doi/10.1130/0016-7606(1961)72%5B621:KHNFOM%5D2.0.CO;2 %N 4 %! Geol Soc America Bull %R 10.1130/0016-7606(1961)72[621:KHNFOM]2.0.CO;2