| The minerals diamond and ____ are pure carbon allotropes. |
amethyst |
| A red corundum that contains chromium impurities is ____. |
diamond |
| A blue corundum that contains iron and titanium is ____. |
emerald |
| The mineral form of sodium chloride (NaCl) is ____ (rock salt). |
graphite |
| A purple quartz that contains manganese impurities is ____. |
halite |
| The hardest naturally-occurring mineral is ____ (hardness 10). |
pyrite |
| A green beryl that contains chromium impurities is ____. |
ruby |
| The mineral ____ (FeS2) is also known as Fool's Gold. |
sapphire |
