| The hardest naturally-occurring mineral is ____ (hardness 10). |
amethyst |
| A green beryl that contains chromium impurities is ____. |
diamond |
| A very soft mineral (hardness 1) with a greasy feel is ____. |
emerald |
| The minerals diamond and ____ are pure carbon allotropes. |
graphite |
| Pure ____ (SiO2) is colorless and has a hardness of 7. |
halite |
| The mineral form of sodium chloride (NaCl) is ____ (rock salt). |
quartz |
| A blue corundum that contains iron and titanium is ____. |
sapphire |
| A purple quartz that contains manganese impurities is ____. |
talc |
