Minerals

Vocabulary Mineral - a crystalline/inorganic substance made of one pure substance Color - the outer visual appearance of the mineral Streak - color left by a mineral that is scraped on a surface. Luster - a mineral’s ability to reflect light Hardness - how easily a mineral can be scratched Mohs Scale - a scale used to classify minerals according to their hardness Density - a measure of the mineral’s mass compared to its volume (d=m/v)

What is a Mineral? Minerals are the “building blocks” of rocks Rocks are made up of different combinations of minerals Different minerals are formed from different combinations of elements 4 Questions to Ask: Is it a nonliving material? Is it a solid? Does it have a crystalline structure? Is it formed in nature? You must be able to answer “yes” to ALL 4 QUESTIONS in order for something to be a mineral.

2 Groups of Minerals Silicate Minerals Made up of silicon and oxygen The specific type of mineral is determined by the other “ingredients” Make up 90% of the Earth’s crust Nonsilicate minerals Is NOT made up of silicon and oxygen It could have one or the other, but not necessary

Properties of Minerals Color Luster Streak Cleavage/Fracture Hardness Density Other Special Properties

Color The same mineral can come in a variety of colors depending on impurities and exposure. Exposure to air, water, and extreme temperatures can alter the color of a mineral Color is not a reliable way to identify minerals because the color can vary

5. Hardness A mineral’s resistance to being scratched Mohs Hardness Scale includes “references” to help determine a mineral’s hardness Example: Steel nail = 6.5 A steel nail does not leave a scratch on the mineral Harder than a steel nail, > 6.5 A steel nail does leave a scratch on the mineral Softer than a steel nail, <6.5

3. Streak The color left behind when you rub the mineral on a streak plate A small amount of powdered mineral left behind The streak color is not necessarily the same color as the mineral! Streak color is more reliable than mineral color when identifying minerals because the streak color is not affected by exposure to air, water, etc.

2. Luster Luster is the way a surface reflects light Metallic (shiny) Nonmetallic (dull) Minerals can appear nonmetallic if they are dirty, so it’s important to make sure the mineral you are identifying is clean!

4. Cleavage/Fracture Cleavage - when a mineral breaks apart with smooth, flat edges Fracture - when a mineral breaks apart with jagged, uneven edges To test a mineral’s cleavage or fracture pattern, you can use a hammer to break off a small section of the mineral. Using a hand lens or microscope is sometimes necessary to view the cleavage patterns

6. Density Golf ball (high density) vs. tennis ball (low density) Measures how much mass is in a given amount of space Mass divided by volume We can measure a mineral’s mass using a triple beam balance We can measure a mineral’s volume using a graduated cylinder Mass (grams, g) Volume (milliliters, mL or cubic centimeters, cm3)

7. Other Special Properties Magnetism Reactivity Taste Fluorescence Radioactivity Optics

What is a Mineral? Minerals are naturally occurring solid substances that are made up of only one substance. Minerals are “inorganic” (nonliving)/crystalline” substances Minerals are classified by characteristics such as color, hardness, streak, and luster Color- The color of a mineral can set it apart from other minerals. Some minerals are the same color and must be investigated further to determine their composition Hardness - When would you use the Mohs Scale? -When you’re trying to identify a mineral based on its hardness

What is a Mineral? Streak - Streak is the colored powder left behind when a mineral is scraped on a surface. Does the “streak” always match the mineral’s color Luster Luster is a measure of how much light the mineral reflects… like a mirror Luster can be either metallic, non-metallic, earthy, or glassy