EARTH'S UNDERGROUND STOREHOUSE 195 



atoms, aiid they associate together to make those 

 pretty Uttle yellow cubes of '' Fool's Gold." Iron is 

 not found with sulphur only. It makes friends also 

 with other minerals, and then it takes a different 

 shape and color. When it combines with oxygen it 

 is black, as one would expect iron to be, and often 

 rainbow colors glow upon the shining surface of the 

 black crystals. 



No one has ever yet found iron all alone. We 

 know that it is in the rocks, but it is so mixed with 

 their substance that we can never find it. But the 

 rain water can and does find it. The water coaxes 

 the iron out and carries it away, leaving it in some 

 convenient place. Now as iron does not like to be 

 alone, it makes friends with other minerals before it 

 will stay comfortably and accumulate in the cracks 

 and openings that are like little shelves in a store- 

 room. 



Gold is stored away in many a crack and crevice. 

 It seems to' take quartz as one of its friends, for these 

 two minerals are often found together. Only, in- 

 stead of combining with the quartz as iron does with 

 sulphur or with oxygen, the gold nestles down quite 

 comfortably beside the quartz when the under- 

 ground water leaves them both in a crevice. 



Often those cracks are large, but the under- 

 ground water works away until in time the fissure is 

 all filled with quartz in which tiny flecks or small 

 lumps of gold are nestling quite cosily. 



Perhaps this gold remains hidden in the ground for 

 a long, long time. But nothing in this world remains 

 always the same. God's law is the law of change 



