Created by. Write. Mineral Identification Key - Common Minerals-Samples: NOTE- This is a Re-posted Product - A nice introduction Mineral Identification Key, contains over 30 commonly used lab minerals. When found as red corundum, it is called ruby. 8 testing tools. (Hint: It is most likely found on your dinner table.). However, their other properties they are completely different. Figure 1. Sulfides like Galena, which is seven times more dense than water, will have a notable heft. However, some quartz crystals have so many flaws that instead of exhibiting conchoidal fracture they simply exhibit irregular fracture. Except for the native element class, the chemical basis for classifying minerals is the anion, the negatively charged ion that usually shows up at the end of the chemical formula of the mineral. Some sulfides are mined as sources of such metals as zinc, lead, copper, and tin. Identifying luster takes a little practice. 4 56 Mineral (Carbonate) Not metallic -- Bubbles in HCL. Another way to test magnetism is to see if your specimen attracts a compass needle. Luster ranges from metallic (highly reflective and opaque) to dull (nonreflective and opaque.) You know then that the mineral’s hardness is between 5 and 6. Minerals are classified according to their chemical properties. Identification Mineral identification is a process of elimination based on determinations of physical properties. Mineral Identification Worksheet Part 1: Recording Observations In the chart below, record your observations of each test for the seven minerals. Grain Size: Coarse grains are visible to the naked eye, and the minerals can usually be identified without using a magnifier. He works as a research guide for the U.S. Geological Survey. The Mohs hardness scale is based 10 reference minerals, from talc the softest (Mohs hardness of 1), to diamond the hardest (Mohs hardness of 10). A diamond, on the other hand, has a hardness of 10. Always check for luster on a fresh surface; you may need to chip off a small portion to expose a clean sample. Calcite, CaCO3, and dolomite, CaMg(CO3)2, are carbonate minerals. Minerals are naturally occurring, inorganic solids with a definite chemical composition and a crystal lattice structure. Halite breaks between layers of sodium and chlorine to form cubes with smooth surfaces (Figure 6). Heft describes how heavy or dense a mineral feels in the hand. To determine cleavage and fracture, you'll need a rock hammer and a safe place to use it on minerals. Examples include iron oxides such as hematite, Fe2O3 and magnetite, Fe3O4, and pyrolusite, MgO. Mica has cleavage in one direction and forms sheets (Figure 7). The Mineral Identification Key: Step 1: Is the Luster Metallic or Submetallic? 11)Many other more difficult tests can be performed once students understand the basic principles of identification. Is it a pale or deep shade? Different types of non-metallic luster are described in Table 1. The most common mineral that is strongly magnetic is the mineral magnetite. For example cleaned polished pieces of chrome, steel, titanium, copper, and brass all exhibit metallic luster as do many other minerals. It's the hardest material known. Match. A mineral may exhibit 100 cleavage surfaces parallel to each other. To compare the hardness of two minerals see which mineral scratches the surface of the other. Through trial and observation, you can determine your mineral's hardness, a key identification factor. The chemical formula and crystal lattice of a mineral can only be determined in a laboratory, but by examining a mineral and determining several of its physical properties, you can identify the mineral. While a mineralogist might use a high-powered microscope to identify some minerals, most are recognizable using physical properties. If a mineral has space while it grows, it may form natural crystals, with a crystal shape reflecting the geometry of the mineral’s internal crystal lattice. Those represent a single cleavage because the surfaces are all oriented in the same diretion. d. A mineral can only be subjected to a few tests before it degrades. You may copy it, or any part of it, for non-commercial, personal use. Minerals may have characteristic fractures (Figure 9). A cleavage direction will show up as a smooth, shiny, evenly bright sheen of light reflected by one set of parallel surfaces on the mineral. Dolomite, found in marble, will fizz actively if dropped in a small bath of acid, for example. Match. Figure 6. Learn. You'll want to use a strong magnet. Remember to distinguish luster from color. b. Gravity. (b) Quartz is not sparkly and has a vitreous, or glassy, luster. This outcome gives you the background needed to understand the terms used in identifying minerals. Pyrite, for example, FeS2, is a sulfide mineral. So color can help, but do not rely on color as the determining property. To check streak, scrape the mineral across an unglazed porcelain plate (Figure 5). Real gold, as seen in Figure 2, is very similar in color to the pyrite in Figure 1. Minerals with a Metallic Luster . Complete, up-to-date, mineral database containing 4,714 mineral species descriptions and comprehensive picture library of images. Calcite is soft, and will not scratch glass. (a) Diamond has an adamantine luster. In introductory geology, the key fracture types to remember are irregular, which most minerals exhibit, and conchoidal, seen in quartz. Recall that a mineral is defined as naturally occurring. Calcite has three cleavage directions which meet at angles other than 90°, so it breaks into solid pieces with perfectly flat, smooth, shiny sides. One of the things mineralogists must do is identify and categorize minerals. Earthy to metallic luster. Both are usually colorless, with a glassy luster. The physical properties of minerals are related to their chemical composition and bonding. Cleavage describes the way a mineral breaks. To understand rocks you need to become familiar with minerals and how they are identified. Most minerals in the earth’s crust and mantle are silicate minerals. This mineral is shiny, very soft, heavy, and gold in color, and is actually gold. Find a mineral that has properties that match Sample A. MINERAL IDENTIFICATION KEY by Alan Plante & Donald Peck We wish to make this key available to one and all in the hope of correct identification of minerals in collections, rock gardens, and on windowsills everywhere. Mineral Identification Key by Alan Plante, Donald Peck and David Von Bargen, Mineralogical Society of America. 24) to identify a mineral that is nonmetallic, dark colored, harder than glass, lacks cleavage, and is green in color. For example, powdery talc has a Mohs hardness of 1; you could crumble it between your fingers. It may take several guesses to get it right. Calcite is easy to identify even without testing the reaction to HCl, by its hardness, luster and cleavage. All rocks except obsidian and coal are made of minerals. These have the polyatomic phosphate ion, (PO4)3–, as the anion. zoe_branch1. Another important mineral identification technique is to determine a mineral's hardness. Calcite fizzes or effervesces as the HCl solution dissolves it and creates CO2 gas. Fizz refers to the effervescent reaction of certain carbonate minerals in the presence of an acid like vinegar. PLAY. D 9. We will emphasize your ability to observe and test for these properties over your ability to merely name the mineral, although that is the overall goal. The Rock Key is much better for his input than it otherwise would have been. Pearly luster refers to a subtle irridescence or color play in the reflected light, same way pearls reflect light. All minerals are crystalline, but only some have the opportunity to exhibit the shapes of their crystals, their crystal forms. The final step in mineral identification is to take your list of characteristics and consult … Close observation and perhaps a magnifying glass are all you need for this step in the mineral identification process. This Mineral Key is designed and intended for use on-line. Color is a fairly reliable indicator in the opaque and metallic minerals like the blue of the opaque mineral lazurite or the brass-yellow of the metallic mineral pyrite. Diamonds are popular gemstones because the way they reflect light makes them very sparkly. Quartz (2) Many light colors Answer the question(s) below to see how well you understand the topics covered in the previous section. In tables 1–3, hardness is measured on Mohs Hardness Scale. Observe and measure the properties of a mineral sample, and then use a key to identify the mineral. You can understand the properties of a silicate mineral such as crystal shape and cleavage by knowing which type of crystal lattice it has. PO Box 342, Huger, South Carolina 29450 843-216-8189 843-216-8352 rockinfo@minimegeology.com www.minimegeology.com. Luster describes the way a mineral reflects light. Are the individual crystals shiny or dull? Quartz, for instance, forms six-sided crystals, showing the hexagonal symmetry of its crystal lattice. Terms in this set (16) Calcite (1) Comes in many white colors White streak Hardness = 3 3 directions of cleavage not at 90 degrees Nonmetallic-glassy luster Reacts to HCl. Garnet Garnet is a group of silicate minerals with six distinct varieties. Ruby & Sapphire – These precious gemstones are the same mineral, corundum. Density describes how much matter is in a certain amount of space: density = mass/volume. Observe and measure the properties of a mineral sample, and then use a key to identify the mineral. It came with over 150 pieces and 30 different types of ricks and minerals to identify. Taste can be used to identify evaporite minerals (minerals formed by evaporation) like halite or rock salt because they have distinctive tastes. At a glance, calcite and quartz look similar. Cleavage is the tendency of a mineral to break along certain planes to make smooth surfaces. Students can observe the color, luster, shape, density, hardness, streak, and reaction to acid for each mineral. Minerals with dull luster reflect very little light. This rough diamond shows its octahedral cleavage. (John Wiley & Sons Inc.). There are two complicating factors to remember here: (1) minerals do not always form nice crystals when they grow, and (2) a crystal face is different from a cleavage surface. Minerals that are opaque and shiny, such as pyrite, have a metallic luster. … Some minerals, such as quartz, form smooth curved surfaces when they fracture. Have a pen and paper or a computer handy to record your notes. A magnifier is also handy, but not required. Many minerals share physical properties in common. Test. MINERAL IDENTIFICATION FLOW CHART This can be tested by seeing if a small magnet responds to the mineral. EPICENTER LAB #1 Use the mineral identification key (see Figure 1. Color: a. Are there lines (striations) running across the minerals? A mineral with visible layers, like Rhodochrosite, has a banded habit. Irregular fracture is a standard term for fractures that do not exhibit any of the qualities of the other fracture types. Some exotic or rare minerals are excluded to allow students to successfully identify lab samples. 9 ) assess the degree of a mineral may exhibit 100 cleavage surfaces in another direction you look it. 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