Waco Gem and Mineral Club, Waco, Tx

1.4 The Three Rock Types


1.4: The Three Rock Types

In this activity, kids would be expected to:

explain the differences among the three basic rock types of igneous, sedimentary, and metamorphic and how these different rock types typically form

identify specific examples of each rock type

build a small collection of representative samples

The three basic rock types are:

Igneous. Igneous rocks are formed by crystallization of magmas, either deep beneath the surface of the earth (granites) or extruded (lavas, obsidian, ash). Examples: granite, basalt, rhyolite, obsidian, pumice, scoria, diorite, gabbro, andesite, tuff

Sedimentary. Sedimentary rocks are formed by sediments (gravel, sand, mud, etc.) created by the eroding action of wind, water, or ice breaking down older rocks or by minerals precipitating out of water. Examples: mudstone, shale, sandstone, conglomerate, limestone, dolomite, coquina, gypsum, diatomaceous earth

Metamorphic. Metamorphic rocks have been changed by heat and/or pressure and other earth forces. Examples: slate (formed from shale), schist (formed from shale, more intensely altered than slate), quartzite (formed from sandstone), marble (formed from limestone), serpentine, hornfels, gneiss

For this activity you can use the following fill-in-the-blank page.

Note: Kids can use this activity toward satisfying requirements for the Earth Processes badge simultaneously (Activities 10.1, 10.3, 10.4, and 10.5)