| A purple quartz that contains manganese impurities is ____. |
amethyst |
| Pure ____ (SiO2) is colorless and has a hardness of 7. |
emerald |
| A red corundum that contains chromium impurities is ____. |
graphite |
| The mineral form of sodium chloride (NaCl) is ____ (rock salt). |
halite |
| The minerals diamond and ____ are pure carbon allotropes. |
quartz |
| A green beryl that contains chromium impurities is ____. |
ruby |
| A very soft mineral (hardness 1) with a greasy feel is ____. |
sapphire |
| A blue corundum that contains iron and titanium is ____. |
talc |
