140 NOTES ON COLLECTING MINERALS. 



one who has given special attention to the study of mineralogy and 

 geology, and has himself collected the specimens : rock-specimens 

 collected here and there, and without correlative information as to 

 the geological structure of the district, are rarely worth the trouble 

 and expense of transport. But if trouble and expense are to be left 

 entirely out of account, a traveller in a region which is comparatively 

 unknown, or which contains neither mines nor quarries, may occa- 

 sionally be of service by collecting material representative of the 

 rocks met with during his journey. Such material should be taken, 

 not from the margin of the rock which has been long exposed to the 

 miction of the weather and is more or less altered, but from the inner 

 part showing uniformity of character. To bi-eak off such specimens, 

 the traveller should provide himself with a hammer of which head 

 and shaft are reasonably proof against fracture. " Mineralogical 

 hammers" are articles of commerce, and are of vaiious weights and 

 sizes ; the head is of well-tempered steel, one end of it being flat 

 and square with an edge about 1 inch long, the other end having 

 the shape of a chisel, the chisel-edge, also about 1 inch in length, 

 being at right angles to the shaft : for most purposes a hammer of 

 2 pounds' M^eight is sufficient. Strong chisels, 4 or 5 inches long, are 

 also occasionally useful. A small trimming-hammer, from | to 

 I pound in weight, is convenient for use in the reduction of 

 specimens to a proper shape and size. The size adopted for the 

 specimen must depend largely on the sizes of the individual mineral 

 constituents of the rock, since the specimen is to illustrate the 

 average characters of the mass, and also on the conveniences for 

 transport : a good average size, if the specimens are intended for 

 exhibition, is, length 4 inches, breadth 3 inches, thickness from 

 i to 1 inch. As rock-material is very heavy, the reduction in 

 size should be made at the place itself ; another piece of the rock 

 can then be immediately got, if by any mischance the specimen 

 be spoiled in the course of the tiimming. Where a rock shows 

 variations of character, specimens should be selected in illustration 

 thereof. 



The interest of a rock-specimen lies very largely in the relations 

 of the mass of which it is a part to the other rock-masses in the 

 district ; unless information as to the locality of the mass to which 



