Quartz and Smoky quartz

Quartz noun - A hard glossy mineral consisting of silicon dioxide in crystal form; present in most rocks (especially sandstone and granite); yellow sand is quartz with iron oxide impurities.

Smoky quartz and quartz are semantically related. In some cases you can replace phrase "Smoky quartz" with "Quartz", this terms are similar.

Smoky quartz noun - A smoky yellow or brown quartz.

Quartz and smoky quartz are semantically related. You can use "Quartz" instead a noun phrase "Smoky quartz".