Presentation on theme: "Chapter 2 – Section 2 Mineral Identification Please open your book to page 36. Please take notes over the yellow slides!"— Presentation transcript:
1 Chapter 2 – Section 2 Mineral Identification Please open your book to page 36. Please take notes over the yellow slides!
2 Identifying MineralsHow do you recognize someone you know? You may be able to identify them by their hair color, height, weight, facial features, etc.Individual minerals also have characteristics that distinguish one from another.
3 Physical Properties Mineral Appearance & Color Hardness Luster Specific GravityStreakCleavage and Fracture
4 Mineral Appearance & Color Two obvious clues used to identify mineralsThese clues are not enough to correctly identify a mineral
5 Mineral Appearance & Color For example – Which one of the following is gold?
6 Mineral Appearance & Color The one on the left is gold and the one on the right is pyrite (also known as fool’s gold).Because they both look like gold, you cannot go just go by appearance and color to identify the mineral.Other tests need to be performedGoldPyrite (fool’s gold)
7 Hardness A measure of how easily a mineral can be scratched Talc is so soft it can be scratched with your fingernail.Diamonds are the hardest substance on Earth and can only be scratched by other diamonds.So how do we tell how hard a mineral is?
8 Moh’s Hardness Scale (pg. 37) A scale developed by Austrian scientist Friedrich Mohs that lists a list of common minerals and their hardness.
9 Let’s say you have a clear, whitish material that you know is either fluorite or quartz…but your not sure because they have the same appearance and color.You try to scratch it with your fingernail but it doesn’t scratch. So you know that whatever it is, it has a hardness greater than 1.
10 You then try to scratch it with the iron nail and you are able to scratch the surface. So you can conclude that the hardness of the clear, whitish material has to be greater than 2.5 but lower than 4.5.You can determine that the hardness of the unknown material is between 3 and 4. Well you already know that quartz has a hardness of 7 so the mystery material has to be fluorite.FluoriteQuartz
11 Let’s Take Some Notes!! Appearance & Color Hardness These clues are NOT enough to correctly identify a mineral HardnessA measure of how easily a mineral can be scratched
12 Luster The way a mineral reflects light. Either metallic or nonmetallic
13 If it’s shiny like metal – it’s metallic HematiteGraphitePyriteIf it’s dull, glassy, pearly, or silky - it’s nonmetallicBiotite(Pearly)Talc(Silky)Obsidian(Glassy)
14 Let’s Take Some Notes!! Luster The way a mineral reflects light (can be metallic or nonmetallic)
15 Specific GravityThe specific gravity of a mineral is the ratio of its weight compared with the weight of an equal volume of water (very similar to density).Gold has specific gravity of 19It means gold is 19 times heavier than water.19 times heavier
17 Let’s Take Some Notes!! Specific Gravity The ratio of the minerals weight compared to the weight of an equal volume of water (similar to density)
18 StreakWhen a mineral is rubbed across a piece of porcelain tile (called a streak plate). A streak of powdered mineral is left behind.
19 The streak test only works for materials that are softer then the plate. The streak plate has a hardness of 7 so you can only test minerals that have a hardness below 7.Gold and pyrite can be determined using a streak plate. Gold leaves a yellow streak and pyrite leaves a greenish black or brownish black streak.Some minerals may appear as one color but leave a completely different color streak.Some minerals will leave a streak on paper…like the graphite in your pencil
20 Let’s Take Some Notes!! Streak The color of the mineral when in powdered form (streak plate)
21 Cleavage Cleavage is the way that mineral breaks. Minerals that break along smooth, flat surfaces have cleavage.The way the atoms are arranged make for a smooth, clean break.Mica has cleavage
22 FractureMineral that breaks uneven, rough, or jagged surfaces have fracture.Quartz has fracture
23 If you were to take a layered cake and separate its layers, we would say that the cake has cleavage. But if we were to take our hand and jab it into the cake and pull it out, we would say that the cake has fracture.
25 Let’s Take Some Notes!! Cleavage & Fracture Cleavage – minerals that break along smooth flat surfacesFracture – minerals that break unevenly & jagged
26 Other PropertiesSome minerals are magnetic, such as magnetite, which is attracted to magnets.In calcite – light forms two separate rays as it passes through causing you to see a double image.Calcite will also fizz if you put some drops of hydrochloric acid on it.