PLATE XLIV. 



FIG. 1. 

 ZIRCON. 



BAGSHOT SANDS, HAMPSTEAD HEATH. 



Magnified 100 diameters. 



FIG. 2. 

 CYANITE. 



BAGSHOT SANDS, HAMPSTEAD HEATH. 



Magnified 100 diameters. 



This mineral is represented by cleavage flakes. Those flakes which are 

 parallel to the first cleavage (100) give an extinction angle of about 30 (26 to 

 83) referred to the trace of the second cleavage (010) and are seen, in con- 

 vergent polarized light, to be approximately at right angles to a negative 

 bisectrix. Those parallel to the second cleavage give an extinction of only 3 or 4 

 referred to the trace of the first cleavage. The rectangular form of many of 

 the flakes is due to a separation parallel to 001. 



FIG. 8. 



TOURMALINE. 



BAGSHOT SANDS, HAMPSTEAD HEATH. 



Magnified 100 diameters. Drawn with polarizer only; short axis right and left. 



FIG. 4. 

 RUTILE. 



BAGSHOT SANDS, HAMPSTEAD HEATH. 



Magnified 100 diameters. 



A, b and c represent characteristic twins of rutile. The mineralogical com- 

 position of the sands of Hampstead Heath lias been described by Mr. DICK (Nature, 

 Vol. XXXVI., p. 91), and figures 1, 2, 3 and 4 are drawn from his preparations. 



FIG. 5. 

 KAOLINITE. 



AMLWCH, ANGLESEA. 



Magnified 50 diameters. 



This mineral was analysed by Mr. TOOKEY (see Dr. PERCY on Fuel, &c., 1875, 

 p, 93) 5iO., 46-53 ; Al fl 8 . ^8-98 ; H 2 (by diff.), 14-54. 



FIG. 6. 

 ANATASE. 



CLEVELAND IRONSTONE. 



Magnified 80 diameters. 



The forms only of the crystals are represented. The larger crystals are opaque 

 except at the edges. A is a crystal showing only the form (111) ; It and c are 

 combinations of the forms (111) and (001) ; d shows the characteristic sthation due 

 to the oscillatory combination of (111) and (001). E and / are merely the outlines 

 of two aggregates. 



