Rocks and Minerals

Rocks and Mineral Samples

Rock and mineral specimens from my collection. Some of the pieces were purchased from dealers.

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

Tourmaline (Schorl)

Mohs Hardness 7.0-7.5
Specific 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

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

Garnet

Mohs Hardness 6.5 - 7.5
Specific 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.

Epidote

Mohs Hardness 6-7
Specific Gravity 3.3-3.5

These pieces were found at the Caledonia Mine near Mass city, Michigan.

Calcite

Chemical formula Calcium carbonate (CaCO₃)
Mohs Hardness 3
Specific Gravity 2.71

This specimen was found at the Caledonia Mine near Mass city, Michigan.

Calcite (Optical)

Gypsum

Chemical formula Hydrated calcium sulfate (CaSO₄*2H₂O)
Mohs Hardness 1.5-2
Specific Gravity 2.35

Feldspar

I found this specimen in 2009 at the Brushy Creek Aquamarine Mine, located near Spruce Pine, NC.

Mica Sheet

This 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.

Copper

Chemical formula Copper (Cu)
Mohs Hardness 2.5-3
Specific Gravity 3.93

These pieces were found at the Caledonia Mine near Mass city, Michigan.

Pyrite

Chemical 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.

Tourmaline, Feldspar and Quartz

I found this specimen in 2009 at the Brushy Creek Aquamarine Mine, located near Spruce Pine, NC.

Quartz Samples

Quartz

Chemical formula Silicon dioxide (SiO₂)
Mohs Hardness 7.0
Specific Gravity 2.65

Smokey Quartz

Rose Quartz

Amethyst Quartz

Rock and Mineral Definitions

Cleavage The tendency of some minerals to break along certain planes.
Crystal Habit The shape in which individual crystals grow and the manner in which crystals grow together in aggregates.
Fracture The way in which a mineral breaks other than along planes of cleavage.
Hardness The resistance of a minerals surface to scratching. Can be evaluated using the Mohs scale of hardness (see right column).
Lava Magma flowing out of a volcano.
Luster The manner in which a mineral reflects light.
Magma Molten rock. Temperatures in the range of 700*c to 1300*c. Consists of silicon, oxygen and other minerals.
Mineral A naturally occurring, inorganic solid with a definite chemical composition and a crystalline structure.
opaque A material that blocks the passage of light.
Polymers Very large molecules.
Silicates Minerals that contain both Si and O.
Specific Gravity The weight of a substance relative to the weight of an equal volume of water.
Streak The color of a fine powder of a mineral. Scratch a mineral sample on a streak plate to make streak.
Translucent A material that permits the passage of light.
Twinning Two or more crystals that have grown together in a symmetrical manor.
Viscosity Resistance to flow.

T-Shirts and Other Gifts for Rockhounds

Just a few of the natural science gifts available at History and Science T-shirts and Gifts.

	Tyrannosaurus rex Skull T-Shirt Photograph 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.
	Beware of The Rockhound T-Shirt Humorous 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.
	Please, Do Not Feed The Rockhound T-Shirt Humorous 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'.
	Arrowhead Wall Clock Unique wall clock featuring a Native American arrowhead! This artifact was found in Chelsea, Michigan. Great gift idea for anyone interested in American Indian Culture!
	Tyrannosaurus Wall Clock Wall 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.

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)

Rocks and Minerals