EMIGRANT DIAMONDS IN AMERICA. 865 



jihly unlike anj^thing that they have ever seen. The first result of the 

 search has been the collection of larg-e numbers of quartz pebbles, 

 which are everywhere present, but which are entirely valueless. There 

 are, however, some simple ways of distinguishinf^ diamonds from 

 (|uartz. 



Diamonds never appear in thoroug'hly rounded forms, like ordinary 

 pebbles, for the}' are too hard to be in the least detrree worn b}' con- 

 tact w ith their neitrhbors in the gravel bed. Diamonds always show, 

 moreover, distinct forms of crystals, and these g-enerally bear some 

 resemblance to one of the forms Hgured. They are never in the least 

 degree like crystals of quartz, which are, however, the ones most fre- 

 ([uently confounded with them. Most of the AVisconsin diamonds 

 have either 12 or 48 faces. Cr3\stals of most minerals are bounded 

 by plane surfaces — that is to say, their faces are tlat; the diamond, 

 however, is inclosed by distinctly curving 

 -surfaces. 



The one propertj' of the diamond, however, 

 which makes it eas}' of determination is its 

 extraordinary hardness — greater than that of 

 any other mineral. Put in simple language, 

 the hardness of a substance may be described 

 as its power to scratch other substances when 

 drawn across them under pressure. To com- 



])are the hardness of two substances WC common forms of Diamonds. 



should draw a sharp point of one across a SUr- The African stones most resem- 



, ^ , , ^ , , ble the figure above at the left 



tace Ot the other under a pressure Ot the (octahedron). The Wisconsin 



fingers, and note whether a permanent scratch atones most resemble the figure 



, I,. n^^ 1 1 1 -111 above at the right (dodecahe- 



is left. I he harder substances will alwa^'s dron). 

 scratch the softer, and if both have the same 



hardness the}- ma}^ be made to mutually scratch each other. Since 

 diamond, .sapphire, and ruby are the only minerals which are harder 

 than emery, the}' are the only ones which, when drawn across a rough 

 emery surface, will not receive a scratch. An}' stone which will not 

 take a scratch from emery is a gem stone and of sufficient interest to 

 be referred to a competent mineralogist. 



The dissemination of information regarding the lake diamonds 

 through the region of the moraine .should serve the twofold ])urpose 

 of encouraging search for the buried stones and of discovering dia- 

 monds in the little collections of "lucky stones" and local curios 

 which accumulate on the clock shelves of country farmhouses. When 

 it is considered that three of ihe largest diamonds thus far found in 

 the region remained for periods of seven, eight, and sixteen years, 

 respectively, in the hands of the farming population, it can hardly be 

 doubted that many other diamonds have been found and preserved as 

 local curiosities without their real nature being- discovered. 



