The James River Park System - Richmond, VA

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South Geology Tour

Stop 1b: This Tour Explores Granite

DIRECTIONS: Turn towards the stairs and kneel on the steps. Examine the rock up close. Notice that it has different specks of color.

steps to bridge

Now that you have experienced time, let us examine rocks. Rocks are made up of MINERALS. Different combinations of minerals form different types of rock. Granite is composed primarily of three minerals.

Try to find these three MINERALS:

  1. BIOTITE -- shiny black specks that look like glitter
  2. QUARTZ -- clear or white crystals that look like foggy glass
  3. FELDSPAR -- color varying (brownish pink or white); large bits often have squared edges

minerals

digging deeper

MINERALS occur in nature as inorganic solids with a specific chemical makeup and crystalline structure.

As granite is weathered by the four agents of erosion (WIND, WATER, ICE, and GRAVITY), feldspar and mica become clay, and quartz becomes sand.

Minerals may be more easily identified in granite that is rough than smooth.


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