It's just another way of saying "be useful". When you are in the woods a map and compass would be of use. They would be useful.
Someone that is looking to purchase quartz worktops can purchase them at local stores such as Canadian Tire or Home Depot. For someone that would prefer to shop online, the can do so at the website eBay.
This would be quartz.
Quartz is a mineral not a rock. Fossils can be found associated with quartz in sedimentary rock not inside the quartz.
If someone wishes to persue a career in US politics it would be useful if they undertook a degree in American Studies as it provides them with useful information about American studies.
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Quartz
A magnetic sweeper would be useful in a situation when someone needs to pick up and find metal items, such as iron. This may be useful in steel work companies.
Quartz, with a hardness of 7, will scratch calcite, with a hardness of 3.
Quartz because its harder than calcite and the quartz in thicker.
A non-metallic mineral such as quartz or calcite.
The best anwser would be A, that they contain quartz.