Question

A hollow rounded rock that is lined with crystals is a ______.

Answer 1

A geode is a round hollow rock lines with crystals.

Answer 2

Answer: Geode

Geodes are hollow, semi-circular sedimentary and volcanic rocks which contain masses of mineral matter (sometimes crystals, but not exclusively). These types of rocks are common in some areas of the United States, such as  Indiana, Iowa, Missouri, Illinois, Kentucky and Utah. They are also formed in places such as Namibia, Mexico, Brazil and England.