ON THE MICROSCOPICAL STRUCTURE OF ROCKS. 
19 
the mineralogist, and the physicist the intelligent use of the 
microscope is invaluable, and I need scarcely add, that in this, 
as in every branch of scientific inquiry, every fresh glimpse we 
obtain brings new beauties to light. 
EXPLANATION OF PLATES. 
CXVI. 
Fig. 1. Quartz, Quartziferous-Porphyry, Saulieu, polarised. 
Fig. 2. Sanidine in Domite, Puy de Dome, polarised. 
Fig. 3. Triclinic Felspar, polarised. 
Fig. 4. Chlorite, Chloritic Schist, nat. 
Fig. 5. Biotite, Germany, seen with polariser alone. 
Fig. 6 . Hornblende in Diorite, seen with polariser alone. 
Fig. 7. Augite, Augitic Porphyry, Germany. 
Fig. 8. Olivine, Somma, Vesuvius, &c., polarised. 
Fig. 9. Leucite, Somma, Vesuvius, polarised. 
Fig. 10. Nepheline and Apatite, Katzenbuckel, nat. 
Fig. 11. Nosean, nat. 
Fig. 12. Haematite and Magnetite, nat. 
(All magnified 26 diam.) 
CXVII. 
Fig. 1. Gas Cavities, in Lava, Hecla. 
Fig. 2. Water Cavities, in Quartz, Cornwall. 
Fig. 3. Glass Cavities, in Quartz, Cornwall. 
Fig. 4. Glass and Stone Cavities, in Lava, Hawaii. 
Fig. 5. Calcite, Marble, Ephesus. 
Fig. 6. Aragonite, Marble, Carrara. 
Fig. 7. Chalcedony, Cornwall. 
Fig. 8. Fibrous Zeolite, in Dolerite, Germany. 
Fig. 9. Mica, in Trachyte, Germany. 
Fig. 10. Organisms, in Limestone, Derbyshire. 
Fig. 11. Vegetable Remains, in Coal. 
Fig. 12. Serpentine, Cornwall, 26 diam. 
(Magnified 56 diam . ) 
c 2 
