622 MR. H. H. 1HOMAS ON THE MINERALOGICAL [ Nov. 1902, 
of refraction is low, and this character is useful for purposes of 
identification. 
Fluorspar has been found in the sands from Berry Head ' to the 
west of Torbay, from Budleigh Salterton, and Woodbury Castle ; but 
it has not been noticed in the Pebble-Bed north of the last-named 
locality, nor does it seem to occur in the so-called ‘ Permian Breccias,’ 
or in the beds above the Pebbie-Bed. 
Garnet.—The garnets of these sands occur in irregular but 
somewhat rounded isotropic grains, usually not more than 0°25 milli- 
metre across, but sometimes reaching as much as 0°30 millimetre. 
‘They are of a pale pink colour, and if in large crystals would 
undoubtediy have been of a very deep red. Crystal-outline is 
generally wanting. 
In the Pebble-Bed they are confined to the North of Devon and 
Somerset, occurring only along the line from Uffculm northward to 
Fitzhead. They have not been found to the south, but are common, 
in fact abundant, in all the red beds above the Pebble- Bed. 
Anatase” (Pl. XXXII, figs. 1-5).—This mineral occurs in 
minute, but usually perfect, colourless, transparent tetragonal 
erystals (rarely exceeding 0-10 millimetre in greatest width). The 
habit is in most cases tabular, the base being large and the 
pyramids narrow. 
An optically negative axis emerges normally to the basal 
plane (001). Many of the larger grains are turbid and of a yellow- 
brown colour: this turbidity seems to be due to a superficial 
decomposition, possibly resulting in the formation of rutile. 
One example only of an octahedral crystal’ has been noted, and 
that from the sand of Fitzhead. The basal plane on this crystal 
was very small. 
This mineral is not very plentiful in the Pebble-Bed, but is 
fairly constant in its occurrence. It is more plentiful in the sands of 
the Upper Bunter, where it occurs with the same tabular habit. 
Rutile* (Pl. XXXI, figs. 10-13).—This mineral is very preva- 
lent throughout the whole of the Pebble-Bed, and is no less common 
in the beds above and below. Simple crystals are seen to consist 
of the simple tetragonal prism {110} capped by a pyramid {111}. 
The commonest occurrence, however, is in the form of rounded 
prisms with indistinct terminations, and grains. 
The colour is from yellow to amber-red or brown. 
The mineral is often twinned, these twins being mostly poly- 
1 This sand exists as an outlying patch in a fissure in Devonian rocks; from 
analogy in composition to the finer material of the Pebble-Bed, I should suspect 
it to be made up of resorted material derived from that deposit. 
2 W. F. Hume, ‘ Chem. & Micro-mineralog. Researches on the Upper Cre- 
taceous of S. England’ 1895, p. 97; J. J. H. Teall, ‘ Brit. Petrogr.’ 1888, 
pl. xliv, fig. 6. 4 
3 H. L. Bowman, Mineral. Mag. vol. xii (1900) p. 362. 
4 J. J. H. Teall, ‘ Brit. Petrogr.’ 1888, pl. xliv, fig. 4. 
