GRAVITATIONAL METHODS 265 



TABLE 7. (Continued) 



TYPE OF MATERIAL 

 Rock Forming Minerals 



(Femic Minerals)** Normal Range Mean 



Olivine 3.3 - 3.4 3.35 



Diopside 3.2-3.4 3.3 



Apatite 3.2 -Z.2, 3.2S 



Typical Sulphide Minerals 



Cinnabar 8.0-8.2 8.1 



Galena 7.4-7.6 7.5 



Bismuthinite 6.6 -6.7 6.65 



Arsenopyrite 6.0-6.2 6.1 



Chalcocite 5.5 - 5.8 5.65 



Bornite 4.9 -5.4 5.15 



Pyrite 4.9 -5.2 5.05 



Marcasite 4.7-4.9 4.8 



Molybdenite 4.4-4.8 4.6 



Pyrrhotite 4.5 - 4.6 4.55 



Stibnite 4.5 - 4.6 4.55 



Sphalerite 3.5 - 4.0 3.75 



Realgar 3.4-3.6 3.5 



Typical Oxides 



Cassiterite 6.8-7.0 6.9 



Cuprite 5.7 -6.0 5.85 



Specular Hematite 5.1-5.3 5.2 



Franklinite 5.1 - 5.2 5.15 



Chromite 4.3 - 4.6 4.45 



Limonite 3.6-4.0 3.8 



Spinel 3.5-4.1 3.8 



Chalcedony 2.6 - 2.6 2.6 



Bauxite 2.0-2.6 2.3 



Opal 1.9-2.3 2.1 



Miscellaneous Minerals 



Uraninite (Pitchblende) 8.0-9.7 8.35 



Barite 4.3 - 4.6 4.45 



Garnite 3.2 - 4.3 3.75 



Pyroxene 2.8 - 3.7 3.25 



Hornblende 3.0 -3.3 3.15 



Fluorite 3.1 -3.2 3.15 



Biotite 2.7 -3.2 2.95 



Muscovite 2.8 -3.0 2.95 



Oligioclase 2.6 - 2.7 2.65 



Microcline 2.5 - 2.6 2.55 



Native Elements 



Gold 15.6 -19.3 



Platinum 14 - 19 



Silver 10.1 -11.1 



Copper 8.8 - 8.9 



Iron 7.Z - 7.8 



Sulphur 1.9 - 2.1 



Miscellaneous 



Coal, hard 1.4 - 1.8 



Coal, soft 1.2 - 1.5 



Water 1.0 



Ice 0.88 - 0.92 



Petroleum 0.6 - 0.9 



^Mnemonic for ferric or ferrous magnesian. 



