1 / 41

www.middleschoolscience.com 2009 http://www.gc.maricopa.edu/earthsci/imagearchive/index.htm

Minerals and Rocks. www.middleschoolscience.com 2009 http://www.gc.maricopa.edu/earthsci/imagearchive/index.htm. What is a mineral?. S olid Cannot be a liquid or a gas N aturally Occurring Found in nature, not man-made I norganic Is not alive and never was, non-living F ixed composition

elin
Download Presentation

www.middleschoolscience.com 2009 http://www.gc.maricopa.edu/earthsci/imagearchive/index.htm

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Minerals and Rocks www.middleschoolscience.com 2009 http://www.gc.maricopa.edu/earthsci/imagearchive/index.htm

  2. What is a mineral? • Solid • Cannot be a liquid or a gas • Naturally Occurring • Found in nature, not man-made • Inorganic • Is not alive and never was, non-living • Fixed composition • Has a chemical formula, most are formed from compounds of two or more elements, some minerals consist of one element ex. Au • Crystal Form • A definite structure in which atoms are arranged

  3. Questions to ask yourself when determining if an item is a mineral or not: The next few slide shows an assortment of items. As a group, categorize the items as either: Minerals or Non-Minerals. • Is it non-living material? • Is it a solid? • Is it formed in nature? • Does it have a crystalline structure?

  4. Gold

  5. Fossil

  6. Topaz

  7. Bones

  8. Granite

  9. Quartz

  10. Pearls

  11. Talc

  12. Icebergs

  13. Diamond

  14. Coal

  15. Rock Salt

  16. And the answers are… • Minerals • Gold • Topaz • Quartz • Talc • Iceberg* • Diamonds • Non-Minerals • Wood - once living • Fossils – once living • Bone - living material • Granite - intrusive igneous rock • Pearls – made by oysters • Coal - Sedimentary rock • Rock Salt – Sedimentary rock According to IMA – ice is listed as a mineral

  17. What is a mineral? A mineral is a naturally formed, inorganic solid that has a definite crystalline structure.

  18. Mineral Identification Basics • PHYSICAL PROPERTIES HARDNESS HARDNESS is defined as the resistance a mineral has to being scratched - its “scratchability”. Hardness tests are done by scratching one mineral against another. The mineral that is scratched is softer than the other. Pyrite Crystals Hardness of 6.5

  19. Mineral Identification Basics • PHYSICAL PROPERTIES HARDNESS MOH’S SCALE OF MINERAL HARDNESS 1. TALC 2. GYPSUM 3. CALCITE 4. FLUORITE 5. APATITE 6. FELDSPAR 7. QUARTZ 8. TOPAZ 9. CORUNDUM 10. DIAMOND OTHER MATERIALS COMMONLY USED: 2.5 - FINGERNAIL 3 - COPPER PENNY 5.5 - GLASS 6-6.5 - STEEL FILE

  20. These are FLUORITE cleavage fragments. Mineral Identification Basics • PHYSICAL PROPERTIES CLEAVAGE CLEAVAGEis the property of a mineral that allows it to break repeatedly along smooth, flat surfaces. These GALENA cleavage fragments were produced when the crystal was hit with a hammer. Note the consistency of the 90o angles along the edges.

  21. Mineral Identification Basics • PHYSICAL PROPERTIES CLEAVAGE Within this crystalline pattern it is easy to see how atoms will separate to produce cleavage with cubic (90o) angles.

  22. Fluorite has cleavage in four directions Mica has perfect cleavage in ONE direction. A thin sheet of Muscovite seen on edge. Mineral Identification Basics • PHYSICAL PROPERTIES CLEAVAGE These pictures show different cleavage angles and the quality of cleavage.

  23. These 3 directions of cleavage are mutually perpendicular resulting in cubic cleavage. Mineral Identification Basics • PHYSICAL PROPERTIES CLEAVAGE Common salt (the mineral HALITE) has very good cleavage in 3 directions.

  24. Hematite on Streak Plate Mineral Identification Basics • PHYSICAL PROPERTIES STREAK STREAKis defined as the color of the mineral in powder form. Streak is normally obtained by rubbing a mineral across a “streak plate”. This is a piece of unglazed porcelain. The streak plate has a hardness of around 7 and rough texture that allows the minerals to be abraded to a powder. This powder is the streak. Hematite has a reddish brown streak.

  25. Mineral Identification Basics • PHYSICAL PROPERTIES LUSTER LUSTERis defined as the quality of reflected light. Minerals have been grossly separated into either METALLIC or NON-METALLIC lusters. Following are someexamples: Native Silver has a Metallic Luster

  26. Stibnite Galena Pyrite Marcasite Mineral Identification Basics • PHYSICAL PROPERTIES LUSTER METALLIC

  27. Olivine - Peridot Wulfenite Quartz Spinel Mineral Identification Basics • NON-METALLICLUSTER VITREOUS

  28. Asbestos - Silky Apophyllite - Pearly Graphite has a greasy or submetallic luster and easily marks paper. Sphalerite - Resinous Limonite - Dull or Earthy Mineral Identification Basics • NON METALLICLUSTER Miscellaneous Lusters

  29. Mineral Identification Basics • PHYSICAL PROPERTIES COLOR The COLORof a mineral is usually the first thing that a person notices when observing a mineral. However, it is normally NOT the best physical property to begin the mineral identification process. Following are some examples of color variation within mineral species followed by minerals that have a distinctive color: Various colors of CALCITE.

  30. Amethyst Ionic Iron Hematite Inclusions Chlorite inclusions Clear - Without Impurities Mineral Identification Basics • PHYSICAL PROPERTIES COLOR Various colors of Quartz.

  31. Azurite Sulfur Malachite Turquoise Rhodochrosite Mineral Identification Basics • INDICATIVE COLOR

  32. Mineral Identification Basics • PHYSICAL PROPERTIES SPECIFIC GRAVITY The SPECIFIC GRAVITY of a mineral is a measure of the mineral’s density. It is related to the types of elements that make up the mineral and how they are packed into the mineral’s atomic structure. Gold has a Specific Gravity of 19.2. It is 19.2 times the weight of an equal volume of water. Water has a Specific Gravity of 1. Gold in Quartz

  33. Weight in air Specific Gravity = (Weight in air) - (Weight in water ) Mineral Identification Basics • PHYSICAL PROPERTIES SPECIFIC GRAVITY The SPECIFIC GRAVITY of a mineral is determined by weighing the specimen in air and then weighing it in water. It is the ratio of an object’s density to the density of water.

  34. Mineral Identification Basics • PHYSICAL PROPERTIES TASTE IT IS NOT RECOMMENDED THAT A TASTE TEST BE PERFORMED ON MINERALS AS A STANDARD PROCESS. SOME MINERALS ARE TOXIC. However, the mineral HALITE is common salt and has a unique taste. Halite cubes from Trona, CA

  35. Mineral Identification Basics • PHYSICAL PROPERTIES MAGNETISM MAGNETISMis the ability of a mineral to be attracted by a magnet. This most commonly is associated with minerals rich in iron, usually magnetite. This is a piece of MAGNETITE with a magnet adhering to it. Magnetite is strongly magnetic in that a magnet will easily be attracted to it.

  36. Mineral Identification Basics • PHYSICAL PROPERTIES DIAPHANEITY The manner in which minerals transmit light is called DIAPHANEITY and is expressed by these terms: TRANSPARENT:A mineral is considered to be transparent if the outline of an object viewed through it is distinct. TRANSLUCENT:A mineral is considered to be translucent if it transmits light but no objects can be seen through it. OPAQUE:A mineral is considered to be opaque if, even on its thinnest edges, no light is transmitted. Quartz with Spessartine Garnets

  37. Mineral Identification Basics • PHYSICAL PROPERTIES DIAPHANEITY TRANSPARENT:A mineral is considered to be transparent if the outline of an object viewed through it is distinct. Topaz from Topaz Mountain, Utah

  38. Sylvite from Salton Sea, California Backlit Apophyllite Crystals Mineral Identification Basics • PHYSICAL PROPERTIES DIAPHANEITY TRANSLUCENT:A mineral is considered to be translucent if it transmits light but no objects can be seen through it.

  39. Mineral Identification Basics • PHYSICAL PROPERTIES DIAPHANEITY OPAQUE:A mineral is considered to be opaque if, even on its thinnest edges, no light is transmitted. Schorl - The black variety of Tourmaline

  40. Investigation Question: Which physical characteristics are useful when identifying minerals? Mineral # Mineral # • Record Data • Record Data

More Related