Jan. 24, 2014 Goal: Identify the properties of minerals Pick up notes DO NOW: List the elements found in the following substance: (use your periodic table if you need help!) KAl 2 (AlSi 3 O 10 )(OH) 2 HOMEWORK: none

What is a Mineral? Minerals make up rocks A mineral is a naturally occurring, inorganic solid that has a crystal structure & a definite chemical composition. –Example: Quartz Naturally-occurring = Never man-made –Ex: Like rocks

Inorganic = the mineral cannot come from things that were once living “Non Example”: Coal – it is organic because it comes from plants that lived millions of years ago.

Solid The mineral’s atoms are arranged in a definite pattern. This repeating pattern is called a crystal. Not a liquid or a gas!

CRYSTAL STRUCTURES

Chemical properties Chemical properties refer to how the mineral reacts with an acid. –Example: Calcite (CaCO 3 ), the main mineral in limestone and marble, bubbles when hydrochloric acid is placed on it. CaCO3 and HCl

Physical Properties Identify Minerals Physical Properties include “tests” you can perform on minerals to determine what type of mineral they might be. These include: 1.Streak 2.Hardness 3.Luster 4.Cleavage 5.Fracture

1. Streak Test The color of the mineral’s powder that’s left behind when it is rubbed across a rough surface Example: Pyrite (aka “fool’s gold”) looks like gold, but its streak looks greenish-black

2. Mohs Hardness Scale A scale that ranks 10 minerals from softest to hardest. You can compare unknown minerals to the minerals on this scale Hardness can be tested by a Scratch Test –A mineral can scratch any softer mineral –Mineral can be scratched by any harder mineral –Minerals that have the SAME hardness can scratch each other.

3. Luster Luster describes how light is reflected from the mineral’s surface. What the mineral looks like.

Types of Luster –MetallicEx: Galena –GlassyEx: Topaz –Waxy, Greasy, PearlyEx: Talc –DullEx: Graphite –SilkyEx: Malachite –EarthyEx: Hematite

4. Cleavage One way minerals break Easily split along flat surfaces Ex: Mica & Halite

5. Fracture another way minerals break Break unevenly in irregular ways –Chipped –Shell-like Ex: Quartz –Jagged points Ex: Copper & Iron –Crumbles Ex: Clay

Quartz Lead

3. Density  It’s a calculation (math problem!)  Use a balance to find the mass  Place the mineral in H2O to find the amount of water it displaces. This amount is the volume of the mineral.  To find the density, divide mass by volume  Ex: Sample of Olivine  Mass = 237 g Volume = 72 cm3  Density = 237 g/ 72 cm3 = 3.3 g/cm3

Science Standard S6E5. How Earth’s surface forms b. Minerals make rocks –EX: Granite may be made of many different minerals (feldspar, mica, hornblende, quartz) c. Rocks are classified by how they are formed –EX: Igneous rocks form from magma/lava cooling –d. Different processes change rock & the surface of the Earth –EX: Weathering & Erosion break down rocks & move them to new places