NODULE BEDS. 
17 
In 1847 the Coprolite ” was-first dug. In 1854 the Greensand 
Coprolite ’’ at Cambridge was discovered, and after that time the 
amount raised in Suffolk began to fall off. Mr. Colchester re¬ 
marks that ‘Ghe quality is wonderfully uniform, 56 per cent, 
of phosphate of lime. The average for Cambridge Coprolite is 
58 per cent, phosphate but there is an excess of oxide of iron 
and alumina in the Suffolk, which accounts for the difference 
in price.” 
Dr. A. Voelcker, in his paper on Phosphatic Manures,^ treats of 
the Suffolk Phosphates, and remarks that in commercial 
phraseology, we have to understand by Suffolk-coprolites, or 
Crag-coprolites, or pseudo-coprolites, the mixed fossil bones, fish- 
teeth, and phosphatic pebbles which occur in the Suffolk Crag. 
These phosphatic matters are distinguished from the grey- 
coloured Chalk coprolites by a brownish ferruginous colour, and a 
smoother appearance. They are very hard, and yield on grinding 
a yellowish-red powder. Analysed in the manner usually adopted 
in commercial analyses, the composition of several samples of 
ground Suffolk coprolites may be illustrated by the following 
tabulated results 
G-eneeal Composition of Suffolk Copeolites. 
— 
No. 1. 
No. 2. 
No. 3. 
No. 4. 
No. 5. 
Moisture and a little organic matter 
4-61 
3-80 
4-11 
6-28 
4-74 
Phosphates 
56-52 
60-21 
61-15 
60-99 
44-20 
Carbonate of lime, magnesia, fluo¬ 
rine, &c. (determined by diffe¬ 
rence) - - _ - 
25-95 
21-77 
22-39 
21-74 
20-92 
Insoluble siliceous matter 
12-92 
14-22 
12-35 
10-99 
30-14 
100-00 
100-00 
100-00 
100-00 
100-00 
*^In good samples of Suffolk coprolites the amount of insoluble 
siliceous matter varies from 10 to 14 per cent.; No. 5, therefore, 
appears to be a very inferior specimen. 
Besides fluoride of calcium, they contain a good deal of oxide 
of iron and alumina, which partially, at least, are thrown down 
with the phosphates when the latter are determined by precipita¬ 
tion with ammonia, as is usual in commercial analysis. In this 
case the amount of phosphates will be stated in excess. The true 
value of these pseudo-coprolites, therefore, can only be correctly 
estimated if the phosphoric acid which they contain is accurately 
* On the Chemical Composition and Commercial Value of Norwegian Apatite, 
Spanish Phosphorite, Coprolites and other Phosphatic Materials used in England for 
Agricultural Purposes. Journ, R, Agric. Soc., vol. xxi. pp. 359, 360. (1860.) 
E 60798. B 
