54 



recommended to those who are desirous to know 

 any thing of minerals. 



Pieces of rocks, with the names of the places 

 from whence they came, would be always inter- 

 esting, as we are unacquainted whether many 

 islands, head-lands, &c. are granite, limestone, 

 or volcanic. Collections of rocks, with particu- 

 lars concerning them, are highly desirable, in 

 order to determine the relative connection of 

 mountains, islands, &c. 



The soil at the bottom of streams or rivers, 

 if gravel, generally partakes of interesting sub- 

 jects. In India, precious stones occur in such 

 soil: in Africa and South America, gold, plati- 

 na, diamonds, rubies, sapphires, and topazes, 

 belong to, and are always found in gravel beds, 

 alluvial soil, as is Tin, in the island of Banca. 

 Silver, lead, copper, iron, &c. occur in veins. 



