|Granite, basalt, obsidian, and pumice are ____ rocks.
|The luster of a mineral can be dull, ____, or brilliant.
|Altocumulus and altostratus clouds are at ____ altitudes.
|Coal, limestone, sandstone, and shale are ____ rocks.
|The Earth was formed about 4.5 ____ years ago.
|The ____ tend to flow west to east 7 miles above the U.S.
|Showers and fog tend to precede ____ fronts.
|Cumulus and stratus clouds are located at ____ altitudes.