CELESTINE DEPOSITS OF THE BRISTOL DISTRICT. 163 
weight, and containing beautiful crystals. The crystals vary 
much in size, some being small, while others associated with 
them may reach a length of three to three and a half inches. 
The minerals found with the celestine vary much in different 
localities. In the Gloucestershire district selenite (sulphate 
of lime) is sometimes found closely associated with the celestine 
in some of the nodules. The celestine from Sicily (Girgenti 
Valley), like most minerals from that neighbourhood, is 
associated with sulphur. This celestine contains a very high 
percentage of sulphate of strontium, often as much as 99 per 
cent. 
When making the deep sea lock at Barry the engineer came 
across a thin bed of celestine of a deep blue colour and very 
heavy, while a short distance away when making the tunnel 
on Barry Island another bed was found, the mineral here 
being very white and of low specific gravity as compared with 
the other, this being perhaps due to a large percentage of 
lime. In the deposits at Wapley and at Winford the celestine 
is associated with crystals of quartz. A deposit on the north 
side of Wickwar tunnel rests on the Old Red Sandstone, and 
the lower portion of the celestine bed contains much silica, the 
analysis giving 11 per cent, of sihca, against about IJ per cent, 
usually met with. The celestine frequently contains a large 
percentage of material derived from the bed on which it is 
deposited. 
At Regilberry a bed containing small celestine crystals 
mixed with yellow clay passes gradually up into a very pure 
bed of sulphate of strontium. In the Yate basin very little 
lime occurs in the celestine, but north of the Mountain Lime- 
stone ridge near Wickwar, which perhaps parted two Triassic 
lakes, the celestine contains much more lime, one analysis 
giving 4 per cent. The celestine is sometimes stained red or 
green. 
In a pocket to the east of Yate at the back of the Black 
Swan Inn the celestine is worked to a depth of thirty feet, and 
