A red corundum that contains chromium impurities is ____. |
amethyst |
A purple quartz that contains manganese impurities is ____. |
diamond |
Pure ____ (SiO2) is colorless and has a hardness of 7. |
emerald |
The minerals diamond and ____ are pure carbon allotropes. |
graphite |
The hardest naturally-occurring mineral is ____ (hardness 10). |
halite |
The mineral form of sodium chloride (NaCl) is ____ (rock salt). |
pyrite |
A green beryl that contains chromium impurities is ____. |
quartz |
The mineral ____ (FeS2) is also known as Fool's Gold. |
ruby |