Rock and mineral specimens from my collection. Some of the pieces were purchased from dealers.
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Beryl (Aquamarine)Chemical formula Beryllium aluminum silicate (Be3Al2Si6O18)Mohs Hardness 7.5-8.0 Specific Gravity 2.72 Luster Vitreous - Resinous Cleavage Imperfect Streak White Crystal Hexagonal Fracture Brittle. Produces small, conchoidal fragments. Aquamarine is a blue variety of beryl. Other beryl varieties include morganite (pink), heliodor (greenish yellow), bixbite (red), emerald (green), and goshenite (colerless). I found these specimens at the Brushy Creek Aquamarine Mine near Spruce Pines, North Carolina in May, 2009 |
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Tourmaline (Schorl)Mohs Hardness 7.0-7.5Specific Gravity 3.06 Luster Vitreous Cleavage None Streak White Crystal Hexagonal, with a rounded triangular cross section. Lengthwise striations. Fracture Brittle. Produces small, conchoidal fragments. Schorl is a variety of tourmaline. Other varieties include elbaite, indicolite, rubellite, and dravite. I found these specimens at the Brushy Creek Aquamarine Mine near Spruce Pines, North Carolina in May, 2009 |
 
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Corundum (Sapphire and Ruby)Chemical formula Aluminium oxide (Al2O3)Mohs Hardness 9.0 Specific Gravity 3.95-4.10 Composed of Aluminum oxide, sapphires come in a variety of colors and are some of the hardest natural substances. Red sapphires are known as rubies. Varieties of corundum are valued as gemstones and for use as abrasives. I found these samples near Franklin, North Carolina in May, 2009 |
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GarnetMohs Hardness 6.5 - 7.5Specific Gravity 3.5 - 4.3 Some varieties of garnet are valued as gemstones and for use as abrasives. I found these specimens in 2009 at the Brushy Creek Aquamarine Mine, located near Spruce Pine, NC. |
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EpidoteMohs Hardness 6-7Specific Gravity 3.3-3.5 These pieces were found at the Caledonia Mine near Mass city, Michigan. |
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CalciteChemical formula Calcium carbonate (CaCO3)Mohs Hardness 3 Specific Gravity 2.71 This specimen was found at the Caledonia Mine near Mass city, Michigan. |
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Calcite (Optical) |
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GypsumChemical formula Hydrated calcium sulfate (CaSO4*2H2O)Mohs Hardness 1.5-2 Specific Gravity 2.35 |
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FeldsparI found this specimen in 2009 at the Brushy Creek Aquamarine Mine, located near Spruce Pine, NC. |
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Mica SheetThis sample measures 15cm wide and around 4cm thick. I found this specimen in 2009 at the Brushy Creek Aquamarine Mine, located near Spruce Pine, NC. |
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CopperChemical formula Copper (Cu)Mohs Hardness 2.5-3 Specific Gravity 3.93 These pieces were found at the Caledonia Mine near Mass city, Michigan. |
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PyriteChemical formula Iron Sulfide (FeS2)Mohs Hardness 6-6.5 Specific Gravity 5.0-5.2 Luster Metallic Pyrite is sometimes called 'Fools Gold' because of its appearance. |
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Tourmaline, Feldspar and QuartzI found this specimen in 2009 at the Brushy Creek Aquamarine Mine, located near Spruce Pine, NC. |
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QuartzChemical formula Silicon dioxide (SiO2)Mohs Hardness 7.0 Specific Gravity 2.65 |
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Smokey Quartz |
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Rose Quartz |
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Amethyst Quartz |
Just a few of the natural science gifts available at Explore Store Gifts.
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Tyrannosaurus rex Skull T-ShirtPhotograph of a T-rex skull. Great gift idea for anyone interested in dinosaurs! This design is available on mugs, t-shirts and more. Other skull designs include Triceratops, Hadrosaur, Gorilla, and Human versions. |
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Beware of The Rockhound T-ShirtHumorous design includes the words ‘Beware of The Rockhound' and ‘Owner assumes no responsibility.’ A great gift idea for any Rockhound! This design looks great on posters, cards and t-shirts. |
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Please, Do Not Feed The Rockhound T-ShirtHumorous design includes the words ‘NOTICE - For your own safety! - Please, Do Not Feed The Rockhound!’ This popular design is also available for 'Paleontologist' and 'Geologist'. |
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Arrowhead Wall ClockUnique wall clock featuring a Native American arrowhead! This artifact was found in Chelsea, Michigan. Great gift idea for anyone interested in American Indian Culture! |
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Tyrannosaurus Wall ClockWall clock design featuring an image of a Tyrannosaurus rex skull. Great gift idea for anyone interested in dinosaurs! There are over 30 science and history themed wall clock designs at Explore Store Gifts. Each clock design is available in three clock styles. Other dinosaur designs include Triceratops and Hadrosaur versions. |
Developed by Frederich Mohs in 1812, the Mohs hardness scale is used to identify mineral samples. The scale associates a common mineral with a range from one to ten. The Mohs scale is not a linear scale.
The following table lists ten minerals that comprise the Mohs scale. The number in parentheses indicates the relative hardness. For instance, calcite, '3' on the Mohs scale, is actually nine times harder than talc, which is '1' on the scale.
| Talc | 1 (1) |
| Gypsum | 2 (3) |
| Calcite | 3 (9) |
| Fluorite | 4 (21) |
| Apatite | 5 (48) |
| Feldspar | 6 (72) |
| Quartz | 7 (100) |
| Topaz | 8 (200) |
| Corundum | 9 (400) |
| Diamond | 10 (1600) |
Luster describes a minerals appearance. Specifically, how light reflects from the mineral.