Granite is a coarse-grained, light-colored igneous rock composed mainly of feldspars and quartz; it also contains minor amounts of mica and amphibole minerals (see the accompanying chart titled Generalized Composition Ranges of Common Igneous Rocks). Once students know how to identify the minerals in granite, this simple description enables ...

To identify granite, first ensure its color is relatively light. Then, look closely and make sure you can see individual crystals with the naked eye. Try to identify large amounts of light-colored quartz and feldspar, with smaller amounts of darker mica or amphibole.

Then use the identification chart (Figure 2) to determine the specific name of each specimen. Granite, which should be the first sample, has been filled in on the student sheet. You may wish to do granite with the group, modeling the process you go …

Igneous rocks in this texture are rare or non-existent.

might have been granite, diorite or gabbro before it was metamorphosed. Examine the following examples of gneiss and try to guess what the original rock was. The minerals are the same as in plutonic rocks, including granite, diorite and gabbro: quartz, the feldspars, and biotite or muscovite mica. Diagram of minerals in gneiss

By pressing the ‘grade identification’ button, you will be told if you are completely correct or if you missed any of the characteristics of the rock. You will try again until you get all characteristics and the name correct. You will write down the CORRECT answers for each in the table.

May 17, 2017 · On each of the following pages you will find an image of a rock and a Igneous Rock Identification Chart. Identify the composition by identifying the color and determine the texture by examining the crystal sizes that are present.

Grains are not lined up. They are randomly scattered. The rock is igneous (granite). b. Grains are lined up and appear to be in rows. The rock is metamorphic (gneiss or schist). a. Rock is glassy or bubbly (has small holes). The rock is igneous (basalt or pumice). b. Rock has hard, flat sheets that split off. The rock is metamorphic (slate).

Rocks rich in magnesium (Mg) and iron (Fe) tend to contain olivine, pyroxene, amphibole, and biotite. These minerals tend to be strongly (dark) colored. On the basis of the amount of color versus white, a color index can be set up that relates to the composition.

a) Granite is coarse grained while Gabbro is fine grained. b) Granite contains more quartz and other light colored minerals. c) Granite will scratch glass while Gabbro will not scratch glass. d) Granite has a crystalline texture while Gabbro is glassy. 4. Which of these rocks contains the same minerals as Granite? a) Pumice and Basalt.