A Handbook to the Mineralogy of Cornwall and Devon: With Instructions for Their Discrimination and Copious Tables of Localities

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Heard and Sons, 1871 - Mineralogy - 108 pages
 

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Page 54 - ... 1. Talc. 6. Orthoclase. 2. GypSum. 7. Quartz. 3. Calcite. 8. Topaz. 4. Fluorite. 9. Corundum. 5. Apatite. 10. Diamond.
Page 95 - ... once what is the weight of a quantity of water, equal in bulk to the solid matter in the sand ; and by comparing this with the weight of the sand, we have its true specific gravity.
Page 77 - The organic constituent of this substance (pigotite), the author considers to be derived from the decay of the various plants which grow on the moist moorlands above, and which, being carried by the waters into the fissures of the granite beneath, combines with the alumina of the decomposed felspar ; and when it reaches the air, deposits itself on the roof and sides of the caverns, in the form of layers, varying from a line to two or three inches in thickness.

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