MINERAL FROM JARROW SLAKE. 103 
part, then passing their mouths carefully over it, appeared to lap 
up the exuding sap, visiting others in succession until satisfied, 
(much in the manner of bees visiting flowers), and then direct 
back to their home. This proceeding I saw repeated again and 
again. The thistles could not, I think, have lost their heads 
accidentally, as many that were so mutilated were much below 
their fellows, and were found scattered over the bed, which was 
many yards in length. 
XX.— Description and Analysis of an undescribed Mineral from 
Jarrow Slake. By E. J. J. BRowE.u. 
I received some time ago, from Mr. Howse, a specimen of a 
mineral found during the excavations for the docks at Jarrow 
Slake. At his request I made an examination of it, of which the 
following is the result :— 
Physical Properties.—Of a doubtfully crystalline or regular 
form, [think doubly prismatic; yellowish colour; very porous and 
friable-—Specific Gravity, 2-48; irregular fracture; has a dull, 
roughish, earthy surface. The specimens of crystals were more or less 
eovered with silt, sometimes quite enveloped by it, so as com- 
pletely to hide their form; and owing to their porous nature, the 
silt, in many cases, penetrated quite into the interior of the mass. 
Their chemical composition is as under. 
First sample analysed, (a.) 
Carbonate otelnmessaesesccerccee neste esteeceeee meas 95°15 
Warbonate of) Maamesia. .ccssscsass cescecustaseseseves 3°73 
Insoluble Residue, (silt, &€.)..........2csceeeeseeeseene 1:53 
NW IGTIS FTE He ctan seca acnceordce REReECEdeicol coonoc Eee eneeee 53 
100°94 
Second sample, (b.) 
Warbonate ofbmel vers cesses: csccscsccsecsasccecscecs se 91°53 
Carbonate Ob Masnesia.c..c..c<cscesrceccaccessssice+ee 3°55 
Insoluble Residue, (silt, &¢.) ......c...cssceceseeeees allies 
Moisture vez. ccatese vec occ oedeecsaawoucusdieauesscsseeses 40 
