Limestone
Is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Limestone makes up about 10% of the total volume of all sedimentary rocks. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years.
Granite
First, granite is made of large mineral grains (which is where its name came from) that fit tightly together. Second, granite always consists of the minerals quartz and feldspar, with or without a wide variety of other minerals (accessory minerals). The quartz and feldspar generally give granite a light color, ranging from pinkish to white. That light background color is punctuated by the darker accessory minerals. Thus classic granite has a "salt-and-pepper" look. The most common accessory minerals are the black mica biotite and sometimes black amphibole hornblende.
Biotite
Biotite is a common phyllosilicate mineral within the mica group; more generally, it refers to the dark mica series.
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- The text "GC56VYC Rock Hound" on the first line
- Lying flat on the ground in front of you is a marker in limestone what color of erosion is starting to show on the marker?
- Standing in front of you is a greyish granite marker (tallest stone in front of you), what size is the biotite in the stone. (i.e. = about rice size, about pea size, or large flakes).
- Walking between the two archways you will see red granite stones (small and low), what size is the biotite in the stone. (i.e. = about rice size, about pea size, or large flakes).
- How many red granite stones are in the arch area as you walk?
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