CALCITE O17 
specimen examined, ‘Test for hardness, and notice with 
what comparative ease it is cut into with a knife ; contrast 
with Quartz. Find its place on the scale of hardness 
already prepared. 
Chip off a few fragments from one of the specimens, and 
observe that it is relatively tough, though much more 
brittle than Quartz. Examine the faces of the broken 
fragments, and notice that they are smooth and even, 2.¢., 
the mineral splits up along cleavage planes and does not 
shew fracture. Contrast with Quartz, which shows 
fracture but not cleavage. 
Break up a portion of the specimen still further, and 
caretully examine the fragments. Ascertain that all these, 
though varying in size, have the same shape, and if possible 
make out the form to be a solid bounded by six equal sides 
or faces, each of which is a rhombus. 
Notice that the mineral is crystalline, 
and, if good specimens are available, make 
out the form of the crystal faces. This is 
not a difficult matter in good specimens. 
The crystals will be found to be pointed 
and six-sided, each side or face being a 
scalene triangle. Contrast with Quartz 
Crystal which ends in a six-sided pyramid, 
each face of which is an isosceles triangle. 
Determine the specific gravity as in 
Fig.149— the case of other minerals. Test for taste, 
Calcite crystal. : aie Bs et 
odour, inflammability, and fusibility, 
and ascertain that these are absent. 
Pour a few drops of Hydrochloric Acid on one of the 
specimens. Notice the effervescence due to the liberation 
of Carbon-dioxide. Heat the acid in a test tube and again 
apply. Notice the increased violence of the re-action. 
Treat a piece of Carbonate of Soda in the same way, and 
