D Look up quartz in the Mineral Database (Fig. 3.22) to find a list of the varie

Question

D Look up quartz in the Mineral Database (Fig. 3.22) to find a list of the varieties (var.) of quartz. Then identify cach variety below (Figs. A3.2.1-A3.2.4), and writ its name beneath the image Figure A3.2.1 Figure A3.2.2 var Figure A3.2.3 var Figure A3.2.4 A mineral can be scratched by a masonry nail or knife blade but not by a wire nail (Fig. 3.14) I. Is this mineral hard or soft? 2. What is the hardness number of this mineral on Mohs Scale? 3. What mineral on Mohs Scale has such a hardness? F A mineral can scratch calcite, and it can be scratched by a wire nail. I. What is the hardness number of this mineral on Mohs Scale? 2. Which mineral on Mohs Scale has this hardness?

Explanation / Answer

D. The different vaieties of quartz cystal are identified by their physical properties .

Fig A3.2.1. Amethyst - transparent quartz with purple color.

Fig A3.2.2. Rock crystal - colourless quartz, commonly in distinct crystals.

Fig A3.2.3. Rose quartz - pink colored quartz.

Fig A3.2.4. Smoky quartz - Grey or brown in color.

E. A mineral is scratched by knife, but not with nails.

1. The mineral is hard. Because the hardness of fingernail is 2-2.5 and the knife hardness is 5-6.5. Thus the mineral is harder than the nail but less harder than the knife blade.

2. The mineral hardness in between 2.5 to 5. Thus the hardness number of this mineral on Moh's scale is 3 or 4.

3. The mineral of this hardness of Moh's scale is calcite or fluorite.

The Moh's scale of hardness:

1.Talc

2. Gypsum

3. Calcite

4. Fluorite

5. Apatite

6. Orthoclase

7. Quartz

8. Topaz

9. Corundum

10. Diamond

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