Chap. 7] 



GRAVITATIONAL METHODS 



81 



Table 16 — Concluded 

 DENSITIES OF IGNEOUS ROCKS 



Material 



Anorthosite 



Granite 



Nephelite-syenite 



2. Extrusive Rocks 



(a) Older than Tertiary 

 Diabase 

 Melaphyre 

 Porphyrite 

 Porphyry 

 Quartzporphyrite 

 Quartzporphyry 



(b) Younger than Tertiary 

 Picrite 

 Basalt 

 Andesite 

 Dacite 

 Trachyte 

 Phonolite 

 Rhyolite 



3. Volcanic Glasses 

 Basaltic glass 



Andesite- and porphyrite glass 

 Vitrophyre 

 Obsidian 

 Rhyolite glass 



Locality 



Investigator 



Reich 



Reich 



Reich 



Reich 



Density (a) 



2.64-2.94 

 2.56-2.74 

 2.53-2.70 



2.73-3.12 

 2.63-2.95 

 2.62-2.93 

 2.60-2.89 

 2.55-2.73 

 2.65-2.73 



2.73-3.35 

 2.74-3.21 

 2.44-2.80 

 2.35-2.79 

 2.44-2.76 

 2.45-2.71 

 2.35-2.65 



2.75-2.91 

 2.50-2.66 

 2.36-2.53 

 2.21-2.42 

 2.20-2.28 



Re- 

 marks 



Table 17 

 DENSITIES OF METAMORPHIC ROCKS 



