ECONOMIC GEOLOGY 
course. Any colors of gold would be recorded on a sketch 
map, and they would increase in size and number toward 
the source of the gold. Where the colors are abundant some 
grains of gold would probably be found, and perhaps ovoid 
particles with a spiral mark ; they, from their resemblance to 
the dung of mice, are known as mouse-droppings. They are 
due to a grain of gold having been hammered by pebbles 
into a thin disc, which has been coiled up as it rolled down 
stream ; the outer edge of the disc forms the spiral mark. 
Coarse angular grains are called shed gold because it is thus 
shed from the parent rock. Owing to the softness of gold the 
grains are soon worn smooth, so that shed gold has not 
travelled far. If no gold or only a few colors are found 
beyond a place with shed gold, the prospector infers that he 
has passed its source, and would search for a “ lode ” from 
which the gold may have come. The most likely lode would 
bea vein of quartz ; and any quartz-veins would be examined, 
especially if the quartz contained cavities and were stained 
Srown by oxide of iron. 
If no rock is exposed the search is continued by loaming. 
The prospector has a long cotton bag, perhaps 6 feet long 
and 6 inches in diameter. He digs a regular series of holes 
and places a sample of earth from the bottom of each in 
the loam-bag and ties a string just above each sample ; 
the process is repeated until the bag is full, when it resembles 
a string of sausages. The loam-bag prevents any mistake 
in the order of the samples, which are washed one by one 
in the tin dish at the river side. The results are marked 
on a plan which shows the distribution of the gold. A line 
could probably be drawn on the plan separating the gold- 
bearing from the barren samples. The source of the gold 
should lie near that line. The prospector would next 
search for the lode by costeaning, a Cornish term for open 
trenches, or, if the material be too deep, by a line of pits. 
The * costeans ” would be dug to the bedrock, and should 
expose the lode from which the gold has come. The lode 
would be sampled to determine whether it is rich enough 
to repay working, or whether, until the country has been 
settled, it would be more profitable to work only the alluvial 
material, 
During this prospecting if other valuable metals are