Table 6.2: Properties of Rocks and Minerals Minerals Name Color Hardness Quartz Feldspar Mica Gypsum Calcite ________________________________________ Igneous Rocks Name Color Hardness Andesite Granite Basalt Obsidian ___________________________________________ Metamorphic Rocks Name Color Hardness Gneiss Slate Marble _____________________________________________ Sedimentary Rocks Name Color Hardness Conglomerate Sandstone Shale Limestone _____________________________________________ Question: Based upon your web search, which type of rock is hardest and which type is softest:
Equipment
- Access to the Internet
Introduction
The Earths crust is made up of rocks, which are solid aggregations of materials that have been brought together by geological processes. The fundamental building blocks of rocks are minerals, which are naturally occurring, inorganic solid elements or chemical compounds with a crystalline structure. A crystalline structure is the orderly geometric arrangement of atoms in the mineral. About 2,500 di↵erent minerals are known to exist, but only about 20 are common in the crust. Examples of these common minerals are quartz, calcite, and gypsum.
Each rock-forming mineral has its own set of physical properties because each mineral has (1) a chemical composition, and (2) a crystal structure that is unlike any other mineral. The exact composition and crystal structure of an unknown mineral can be determined by using laboratory procedures such as X-ray diffraction. In this laboratory activity you will learn how to identify minerals by considering some identifying characteristics of large, well-developed mineral crystals.
Igneous rocks are formed by volcanoes. Sedimentary rocks can be organic or inorganic and are layered. Metamorphic rocks are geologically altered.
Hardness is the resistance of a rock or mineral to being scratched. Below is the MOHs Hardness scale. On this scale, Talc is the softest (1) and diamond is the hardest (10).
Table 6.1. Mohs Scale of Hardness
Hardness Number Mineral Example
1 Talc
2 Gypsum
3 Calcite
4 Fluorite
5 Apatite
6 Feldspar
7 Quartz
8 Topaz
9 Corundum
10 Diamond
Procedure
In Table 6.2, do a Google search for each rock to determine its color. Then do a second Google search for the hardness of each rock. For example, “sandstone hardness”. Record color and Hardness for each rock and mineral. If a rock or mineral has variable hardness, input “Var.”
Table 6.2: Properties of Rocks and Minerals
Minerals
Name Color Hardness
Quartz
Feldspar
Mica
Gypsum
Calcite
________________________________________
Igneous Rocks
Name Color Hardness
Andesite
Granite
Basalt
Obsidian
___________________________________________
Metamorphic Rocks
Name Color Hardness
Gneiss
Slate
Marble
_____________________________________________
Sedimentary Rocks
Name Color Hardness
Conglomerate
Sandstone
Shale
Limestone
_____________________________________________
Question: Based upon your web search, which type of rock is hardest and which type is softest:
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