246 
Further Report. 
1 have the honour to submit a further sketch plan and report on the 
phosphate bed's near Mansfield, dealing more fully with the geology, and 
including notes on some new deposits half-a-mile S.E. of the original find. 
Since my recent more thorough examination of both the original and the 
new outcrops, I am able to more fully describe the chert and phosphate 
beds, and to state that they are much older than Silurian, probably as old 
as Cambrian. 
On the eastern portion of the plan are shown the Carboniferous rocks, 
which have the Silurian and Cambrian (?) ones underlying them. The 
Silurian beds are regular in strike, and consist of conglomerates, hard 
siliceous sandstones, coarse ferruginous sandstones and green to brown 
shales. The strike is 135 degrees, and the dip to south-west at 75 degrees. 
Encrinite ossicles were noted in the conglomerates. 
Cambrian (?). —As spem in allotment 14B, parish of Loyola, the 
phosphatic and chert beds exhibit great contortion, and are tortuous in their 
strike; but where taken, as shewn on sketch plan, their strike is 280 degrees 
and dip southerly at 45 degrees. Wavellite occurs in veins in the phos¬ 
phatic beds, and on joint planes in the cherts. 
During my last examination I traced a new outcrop of the chert beds in 
allotments i6a and i6b, parish of Loyola, and here the phosphatic beds 
are narrower, much darker, and the black and green cherts more exposed 
than those in allotment 14B. No wavellite was noted in them, but I found 
fossil fragments of trilobites and braehiopods in a grey phosphatic bed. 
Professor Gregory, D.Sc., F.R.S., has undertaken the examination of a 
collection of the fossil fragments, which, when completed, will probablv 
afford sufficient palaeontological evidence to define the exact geological age 
of the beds. 
The following lithological and stratigraphical evidence points to the beds 
being very old : — 
1. The rocks are black, grey and green cherts, similar to those of 
Heathcotian (pre-Ordovician series), and white, grey and 
black fossiliferous phosphatic rocks. 
2. The grey phosphatic rock contains fossil fragments of trilobites 
and braehiopods, &c., of probably very old forms. 
3. The beds show great contortion and tortuous strike. 
4. They are unconformable to the. overlying Silurian formation, 
which has a regular strike west of north, while the Cam¬ 
brian ( ?) has a very irregular strike, which is nearly east and 
west in allotment 14B. 
5. The Silurian conglomerates contain occasional pebbles and frag¬ 
ments of the cherts, showing that at least the phosphatic and 
chert beds are older than Silurian. 
Analyses of specimens from allotment 14B, parish of Loyola, as made 
by Mr. P. G. W. Bayly, at the Mines Department Laboratory — 
Picked Samples, 
Average Sample 
No. 17, of 
No 18. of 
Wavellite- 
Wavellite- 
bearing - rock. 
bearing rock. 
Percentage. 
Pereentage. 
Insoluble matter 
41 86* 
43 -47 f 
Phosphoric anhydride (P„0 5 ) 
17-36 
17-38$ 
Alumina (Al„0d 
20-84 
2100 
Iron peroxide (Fe 2 0 3 ) ... 
3-42 
.;. 3-14 
Water at 100° C. 
2*02 
1.71 
Water (ignition) 
14-56 
12-31 
100-06 
99 01 
* Contains silica (Si0 2 ), 39 - 64 percent. t Contains silica (Si0 2 ), 40 - 79 percent. 
X Gives orthopliosphoric acid (H,P0 4 ), 23 - 5 per cent. 
