One identifying characteristic of minerals is their relative hardness, which can be determined by scratching one mineral with another. In this type of test, a harder mineral can scratch a softer one, but a softer mineral is unable to scratch the harder one. The Mohs' hardness scale is used to rank minerals according to hardness. Ten minerals are listed in this scale, ranging from talc with a hardness of 1 to diamond with a hardness of 10. On this scale, quartz (number 7) is harder than feldspar (number 6) and is therefore able to scratch it; however, feldspar is unable to make a mark on quartz.
1. Which of the following best states the subject of this passage.
A. The hardness of diamonds.
B. Identifying minerals by means of a scratch test.
C. Feldspar on the Mohs' scale.
D. Recognizing minerals in their natural state.
2. The main idea of this passage is that
A. the hardness of a mineral can be determined by its ability to make a mark on other minerals.
B. diamonds, with a hardness of 10 on the Mohs' scale, can scratch all other minerals.
C. a softer mineral can not be scratched by a harder mineral
D. talc is the first mineral listed on the Mohs' scale
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