[单项选择]The diamond is considered the most famous and valuable jewel in the world. A diamond is a (31) of wealth.
Diamonds were made (32) great volcanic heat and pressure. A volcano is a mountain with a hole on the top. A volcano can be very dangerous because (33) it is active it sometimes (34) and causes great damage.
Diamonds were (35) towards the surface of the earth—millions of years ago by (36) great volcanic explosions. It is in the narrow volcanic pipes (37) diamonds are found, They are also found among the sand and stones of certain river (38) , and in a few places on the floor of the sea. For they were washed (39) the mountain sides by the rain.
Diamonds are very (40) . There are not many diamond pipes or diamond-producing rivers in the (41) . During the last century adventurers from Europe went to Brazil, because they had heard (42) there were diamonds in the River Amazon. Many of these