with trace elements derived from their host minerals
by the radioactive decay of rare igneous rocks
at an earlier period than were their host minerals
from the crystallization of rare igneous material
18. According to the passage, the age of silicate minerals included in diamonds can be determined due to a feature of the
trace elements in the diamond hosts
trace elements in the rock surrounding the diamonds
trace elements in the silicate minerals
silicate minerals crystal structure
host diamonds crystal structure
19. The author states that which of the following generally has a crystal structure similar to that of diamond?
Lamproite
Kimberlite
Olivine
Pyroxene
Garnet
20. The main purpose of the passage is to
explain why it has not been possible to determine the age of diamonds
explain how it might be possible to date some diamonds
compare two alternative approaches to determining the age of diamonds
compare a method of dating diamonds with a method used to date certain silicate minerals
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