Specimen Identification Guide
The following is designed to help you identify common rocks and minerals found in the Upstate of SC and surrounding areas. You will find some practical information about identifying minerals and you will be guided through a few simple tests you can do at home that will assist you with narrowing the possible identification of your specimen(s). You will also find some detailed descriptions and pictures of common minerals from the Upstate area. Reference books that can help you to identify minerals, rocks, rocks, fossils, and meteorites are available for purchase in our gift shop.
(Parents and teachers- this easy, low-cost and entertaining activity is also well suited for a rainy day or the classroom, respectively)
Step 1. Determine if your specimen is an artifact, a fossil, a rock, or a mineral
Let's start with the basics. The first thing to do is to determine if your specimen is an artifact, a fossil, a rock, or a mineral.
Artifacts are objects made by modern or prehistoric humans (e.g., arrowheads and pottery). The Bob Campbell Geology Museum does not identify artifacts. Please click here to learn more about artifact identification resources in South Carolina.
Fossils are any evidence of past life including body parts such as bones, feathers, scales and leaves, or other preserved traces of behavior such as footprints, burrows and excrement. An example of a fossil is Mammuthus columbi (Wooly Mammoth), which also happens to be the state fossil of South Carolina. Also be sure to check out our webpage on the Paleontological Resources of South Carolina.
Fossils are exceedingly rare in the Upstate of SC but are quite common in much of southern portion of the state. However, if what you have is a fossil, you can send a few high-resolution digital photographs to our curator at the following address (email@example.com), or you can drop off your fossil at the museum for identification (download the ID Request form here). Please fill out the form as completely as possible and bring it with you when you drop off your specimen for identification. If your specimen is not a fossil, keep reading below. If you think your specimen may be fossilized bone or wood, please see the description below regarding how to tell the difference.
Rocks are naturally occurring combinations of two or more minerals. There are three broad categories of rocks—igneous, metamorphic, and sedimentary. An example is Winnsboro Blue Granite – an igneous rock composed of the minerals quartz, feldspar and mica that is also the state stone of South Carolina. You can see some examples of rocks common in the Clemson area here.
If your specimen is a rock, you will need to identify the individual minerals that compose it by following the mineral identification guide below. Once you have identified the relative abundance of different minerals in your rock, you can come see examples of common Upstate rocks at the museum or you can refer to an online or other reference for identification. You may also bring your mystery rock to the museum for identification (download the ID Request form here).
Minerals are naturally occurring, inorganic, solids with a specific chemical formula and atomic arrangement. Minerals are classified based on characteristics such as hardness and crystal shape (e.g., hexagonal, cubic). An example is Quartz – Silicon dioxide (SiO2). Quartz is the most common mineral in the Earth's crust. For example, the purple variety of quartz is called amethyst, and is the state mineral of South Carolina. Its crystal shape is hexagonal (6-sided) and its hardness is a 7 (out of 10 on the Moh's scale, see below).
Geologists have documented more than 5,000 different species of minerals! Most minerals are very rare and their identification often requires a mineralogist that is trained in the use of microscopic and other analytical techniques. However, some minerals (e.g., quartz and calcite) are very common. The following guide is intended only to assist you with identifying some of the minerals that are common at the surface in the Upstate of South Carolina.
Step 2. Assemble the following items you may need to assist with your identification:
magnifying glass; iron nail or paper clip; US copper penny; vinegar; magnet; a small piece of glass you don't mind scratching (e.g., a glass bottle or old drinking glass); a small piece of unglazed ceramic floor tile or coffee mug; your fingernail.
Step 3. Assess the characteristics of your mineral specimen
Common Mineral Characteristics
Geologists use a variety of characteristics to classify and identify minerals. Let's cover some of the basics that you will use to help identify your mystery mineral.
Color: Many minerals occur in a very limited number of colors or shades of a single color, and thus, color is an easily identifiable characteristic that can be a good place to start when identifying a mineral specimen. For example, the minerals pyrite and gold are always metallic yellow in color (although they differ in other characteristics such as hardness). Some minerals, for example quartz (see examples pictured below), come in every color of the rainbow and thus, color is not useful for identification of those minerals. Sometimes it is useful to clean minerals (usually with water) and examine them with a jewelers loupe or magnifying glass in order to accurately assess their true color.
Hardness: The hardness of minerals is measured on a relative scale called "The Moh's Scale of Mineral Hardness". The scale consists of 10 minerals of known hardness: 1) talc; 2) gypsum; 3) calcite; 4) fluorite; 5) apatite; 6) orthoclase feldspar; 7) quartz; 8) topaz; 9) corundum; 10) diamond. Talc is the softest and diamond is the hardest. Using known examples of these minerals to attempt to scratch mineral samples of unknown identity can be very useful in determining their relative hardness. For example, the common mineral quartz has a hardness of 7, so any mineral that you can scratch with a quartz crystal has a hardness of less than 7. Pocket knives, paper clips, and iron nails generally have a hardness of 5.5-6.5. Glass can be scratched by any mineral harder than ~5.5. A US copper penny has a hardness of 3.0 and human fingernails have a hardness of ~2.5. By using these common objects you can determine the relative hardness of your mineral specimen with some degree of accuracy. See the following website for a more detailed description of the Moh's scale and how to test mineral hardness (http://geology.com/minerals/mohs-hardness-scale.shtml).
Effervescence: Geologists call the foaming or fizzing that results from gasses released from minerals (in aqueous solution) effervescence. Whereas most geologists use diluted hydrochloric acid to test if a mineral effervesces, most people do not have access to this chemical at home. A relatively good substitute is vinegar or acetic acid. If based on its hardness, you suspect your mystery mineral may be calcite, a very common mineral (see pictures and description below) try the following test. Use an iron nail or knife blade to scratch the surface of your specimen until a small quantity of powder is visible (see photo). Carefully place 2-3 drops of vinegar on the powdered mineral and watch closely for small bubbles and listen carefully for a faint fizzing sound. If your mineral bubbles and fizzes, you probably have a sample of calcite.
Streak: Smooth, unglazed ceramic floor tiles or coffee mugs have a hardness of ~7.0. If your mineral is softer than 7.0 it will leave a streak when scratched across the surface of the ceramic. The color of the streak left behind can be very informative, and sometimes surprising. For example, the common mineral hematite, which is usually some shade of grey, leaves a red to reddish brown streak. However, the streak of most minerals is similar in color to that of the mineral in hand-sample (see the example of galena pictured below).
Magnetism: This one is pretty self-explanatory. If your magnet adheres to your mineral, you definitely have some form of iron mineral, quite possibly magnetite or hematite (see photos below). You will need to investigate streak color and crystal shape to determine what iron mineral you have found.
Crystal habit or shape: The outward appearance of single crystals is directly related to the internal arrangement of the atoms that compose a mineral. There are far too many different crystal habits to describe in detail here. However, the common shapes you will likely encounter among common minerals in the upstate are cubic (see pyrite crystals on left below), hexagonal (see quartz crystals on right below), trigonal, pyramidal, dodecahedral, prismatic, accicular, and botryoidal.
Cleavage and Fracture: This essentially the pattern in which crystals break usually along planes of weakness (see examples below). For example, quartz typically does not cleave along clean planes of weakness, but fractures in what is called a conchoidal pattern (scalloped pattern in obsidian shown below).
Step 4. Compare your specimen to the photos and descriptions of common minerals and other items frequently discovered in the Upstate
Quartz (silicon oxide): A silicate mineral (the most common on Earth!) that comes in a variety of colors (milky, clear, smoky, amethyst, rose) with crystals that are typically hexagonal in shape (often inside geodes or in veins). Quartz is also common as cryptocrystalline or microcrystalline masses (agate, jasper, chert, chalcedony, etc...). Hardness = 7.0; cleavage = no; fracture = conchoidal; luster = vitreous; effervescence = no; streak = no.
Feldspar (potassium and/or sodium aluminum silicates): A relatively large group of silicate minerals including orthoclase, plagioclase, sanidine, microcline, and others. Crystals are typically prismatic, columnar or tabular. Feldspars occur in a variety of colors (white, yellow, blue, green, pink). Hardness = 6.0; cleavage = ~90 degrees; fracture = conchoidal; luster = vitreous; effervescence = no; streak = white.
Calcite (calcium carbonate): a very common mineral, especially in caves and as a secondarily deposited druze. Calcite crystals are typically rhombohedral, scalenohedral or prismatic and come in a variety of colors (most commonly white or yellow but sometimes blue, pink or green). Hardness = 3.0; cleavage = rhombohedral; fracture = conchoidal; luster = vitreous or pearly; effervescence = strong; streak = white.
Hematite (iron oxide): Red, reddish-brown or black mineral with hexagonal or rhombohedral crystals. Hematite more commonly occurs as botryoidal, granular, or concretionary masses. Hardness = 5.5-6.5; cleavage = no; luster = metallic; effervescence = no; streak = brown to red; magnetic after heating. The image below is a sample of granular hematite of the sort commonly found in Upstate SC.
Pyrite (iron sulfide): Also known as fool's gold, this mineral is easily recognizable by its gold coloration. Crystals are typically cubic or octahedral, with crystal faces often striated. Hardness = 6.0-6.5; cleavage = poor; fracture = conchoidal; luster = metallic; effervescence = no; streak = greenish-black; will spark when struck with a hammer.
Beryl (beryllium aluminum silicate): Beryl comes in a variety of colors (grey, yellow, blue, green, pink). Crystals are hexagonal and can be very large (some weighing as much as 25 tons!). Hardness = 7.5-8.0; cleavage = imperfect basal; fracture = conchoidal; luster = vitreous; effervescence = no; streak = white. The specimen below (BCGM 443) is a typical green beryl crystal in a matrix of smoky quartz from Alexander County, North Carolina.
Garnet (iron aluminum silicate): Almandine variety garnets are the most common in the Upstate of South Carolina. Almandine crystals are typically dodecahedral or trapezohedral and are red in color. Hardness = 6.5-7.5; cleavage = no; fracture = subconchoidal; luster = adamantine; effervescence = no; streak = white. The Almandine garnets pictured below are in a matrix of quartz and muscovite mica (BCGM 495; Yancy County, North Carolina).
Mica (hydrous potassium aluminum silicate): Muscovite and biotite mica are the two varieties most often found in the Upstate of SC. These sheet-like minerals are soft and provide the "glitter" that is so common in our mountain streams. Hardness = 2-2.5; cleavage = perfect basal; luster = vitreous; effervescence = no; streak = usually white. The specimens pictured below are typical of the specimens of muscovite mica found in the Upstate of South Carolina.
Fossilized wood versus Fossilized bone: The similar appearance of these two types of fossils can often make it difficult to distinguish between them. Both vertebrate bone and wood are made of cells and tree rings do superficially resemble bones in cross-section. Two simple tests can help you figure out what your specimen might be. First, try lightly hitting your sample with a screwdriver or other metal object. Small pieces of fossilized wood will often make a "chiming" sound when struck (like a china plate). Striking fossil bone usually results in a dull thud. Secondly, if you don't mind getting a little dirty and your specimen is relatively clean, try lightly touching your the tip of your tongue to your specimen. Porous bone will frequently stick to your tongue, whereas fossilized wood (left) typically, will not. The fossil bone pictured below (on right) is from a horse (BCGM 549; Equus sp.; Miocene Eastover Formation of Surry County, Virginia).
Geodes, Concretions and Dinosaur eggs: Although dinosaur eggs have never been reported from anywhere in the Upstate of SC (or neighboring states), rounded geodes and concretions are abundant in some places. Geodes (left image) are typically hollow inside and are sometimes lines with crystals (most often quartz). Concretions (middle image) are typically solid and are frequently composed of siderite (iron carbonate) and sandstone. The best way to determine if your specimen is a geode or concretion is to break one open with a hammer or cut one open with a wet saw. The porous texture of dinosaur eggs (right image; and other types) is quite different and easily recognizable in comparison with geodes and concretions.
Meteorites versus Industrial slag versus Hematite: Iron meteorites (top) are quite rare and can be very valuable. These space rocks are often pitted in a somewhat similar way as a commonly discovered industrial waste product called industrial slag. Slag (middle) is much lighter per unit volume than iron meteorites and is frequently multicolored (blue, red and purple iridescence). Heavy iron meteorites are frequently solid, dark-grey in color. Finally, iron meteorites are strongly magnetic and slag is not. Fee-based meteorite identification service can be found here: http://meteoritetesting.org. Hematite is a common iron oxide mineral found throughout the Upstate. Because of its great density and because of its weak magnetic attraction, it is often mistaken for meteoritic material (see the photos above and at the bottom of the page).
All images are from creative commons or are BCGM specimens.