Minerals, Metals and Gemstones of Pennsylvania

There are about 300 minerals which are known to occur in Pennsylvania. The minerals, metals and gemstones which follow are an alphabetical listing of some of these materials which are native to the Commonwealth:

Agate

Agate is a micro-crystalline variety of quartz with a white to grey, dark blue, orange to red, black, or banded color. It is considered a gemstone.

Albite

Albite is a plagioclase feldspar mineral with a white to grey, bluish, greenish, or reddish color.

Almandine, also called Almandite

Almandine is an iron alumina garnet with a reddish orange to red, deep red, or near purple color in what is usually a deep or dark tone. When cut, almandine is also known as carbuncle . It is considered a gemstone.

Amethyst

Amethyst is a variety of quartz with a light violet or deep purple color. When amethyst is greenish in color it is often referred to as green quartz, prasiolite, vermarine, or lime citrine. It is considered a gemstone.

Andesine

Andesine is a plagioclase feldspar mineral with a white, grey, green, yellow, or flesh red color.

Anhydrite

Anhydrite is an anhydrous calcium sulfate mineral that is colorless to pale blue, or sometimes violet, white, mauve, rose, pale brown or grey if impurities are present.

Anorthite

Anorthite is a plagioclase feldspar mineral that is white, grayish, or reddish in color. This mineral also makes up much of the lunar highlands.

Antigorite

Antigorite is a mineral poly-morph of the serpentine group. It is usually dark green in color, but can also be found in yellowish, grey, black or brown colors. It is sometimes used as a gemstone.

Baryte, also called Barite

Baryte is a mineral comprised of barium sulfate that is usually white or colorless, but can contain light shades of blue, yellow, grey or brown.

Biotite

Biotite is a phyllosilicate mineral sometimes referred to as "black mica." It is dark brown, greenish brown, blackish brown, yellow or white in color.

Calcite

Calcite is a mineral poly-morph of calcium carbonate. It can be colorless, white, grey, yellow or green in color. Calcite crystals have significance in some religious traditions.

Celestine

Celestine is a mineral named for its occasional bluish color. It consists of strotium sulfate and can be colorless, white, pale blue, pink, pale green, black or pale brown.

Chalcopyrite

Chalcopyrite is a copper iron sulfide mineral. It is often confused with pyrite and has a brass yellow color that sometimes appear with a purplish tarnish.

Chamosite

Chamosite is a mineral that is a member of the chlorite group. It may be greenish-grey or brown in color.

Chromite

Chromite is an oxide mineral of a black or brownish color.

Clear Quartz

Common or clear quartz is a silicate mineral which is clear or transparent in appearance. It is a gemstone.

Clinoclore

Clinoclore is a mineral of the chlorite group. As a gemstone clinoclore is known as seraphinite and has a dark green to grey color.

Clinocrysotile, also known as White Asbestos

Clinocrysotile is a soft, fibrous silicate mineral of the serpentine group. It is grey to green in color and most commonly known as asbestos.

Copper

Copper is a soft and malleable reddish-orange colored element that is a naturally occurring, or free metal. The symbol for copper is Cu and its atomic number is 29.

Corundum, also known as Ruby or Sapphire

Corundum is a crystalline mineral form of aluminum oxide. It is considered a gemstone and can be clear and transparent or appear in a variety of colors. Red corundum is referred to as ruby, and all other colors are considered sapphires.

Diopside

Diopside is a monoclinic pyroxene mineral that is considered a gemstone. The colors of diopside can range from its most common appearance of light to dark green, to blue, brown, grey, white or colorless.

Dolomite

Dolomite is a mineral composed of calcium magnesium carbonate. It is white, grey or pink in color.

Downeyite

Downeyite is a mineral which is primarily comprised of the element selenium. Downeyite crystals are colorless, transparent and have a diamond-like luster.

Eastonite

Eastonite is a mineral of the biotite subgroup of mica. Its colors are typically towards the lighter shades of dark mica.

Fayalite

Fayalite is an iron-rich member of the olivine group with greenish yellow, yellow-brown, brown, or pale yellow to amber colors.

Fluorite

Fluorite, also known as Blue John, is a halide mineral which can be colorless, white, purple, blue, green, yellow, orange, red, pink, brown or bluish-black. It is considered a gemstone, but not widely used due to its softness. Fluorite is well known for its thermoluminescence as well as its fluorescence under ultraviolet light.

Forsterite

Forsterite is a magnesium-rich member of the olivine group. It can be colorless, green, yellow, yellow green or white. The gemstone variety of forsterite is known as peridot.

Galena

Galena is a lead ore mineral which is the natural mineral form of lead sulfide. Deposits of galena often contain significant amounts of silver. It is lead grey or silverish in color.

Gold

Gold is an element which is a highly sought-after precious metal. It is a native metal that occurs as nuggets or grains. It is a soft, shiny and malleable metal with a bright yellowish color and luster. The symbol for gold is Au and its atomic number is 79.

Graphite

Graphite is a mineral that is an allotrope of carbon and the most stable form of carbon under normal conditions. It is steel black to grey in color and may be considered a very high grade of coal known as meta-anthracite. It is a conductor and is also used for its lubricating properties.

Gypsum

Gypsum is a common mineral which is very soft and is comprised of calcium sulfate dihdyrate. It is colorless to white in color with yellow, tan, blue, pink, brown, reddish brown and grey tints when impurities are found. In its crystal form selenite, gypsum is considered by some to be a gemstone. It was used during the Bronze Age as a substitute for wood in building construction. In modern times, it is primarily used for building materials and fertilizer.

Halite, also known as rock salt

Halite is the mineral form of sodium chloride. It is typically colorless or white, but it may also be light blue, dark blue, purple, pink, red, orange, yellow or grey in color when impurities are present.

Hematite, also called Haematite

Hematite is a mineral form of iron oxide. Its name is derived from the Greek word for blood. Terrestrial hematite is a mineral usually formed in aqueous regions, which is interesting as it has been discovered in significant amounts on Mars. It is the main ore mined for iron and is black steel, silver-grey, brown to reddish brown or red in color with a rust-red streak; it is more brittle than pure iron, but harder. Hematite is sometimes used for jewelry.

Kaolinite, also known as White Clay

Kaolinite is a layered silicate mineral which is one of the most common minerals found on Earth. This mineral is usually white in color, but can be red, blue or brownish. It is a clay which has many uses included the production of ceramics, porcelain, pipes, paint, and cosmetics.

Lansfordite

Lansfordite is a hydrated magnesium carbonate mineral which usually occurs as colorless or whitish in color.

Laphamite

Laphamite is a secondary mineral formed as a product of burning anthracite coal mine waste. It is dark red to brownish in color.

Lizardite, also called Orthoantigorite

Lizardite is a mineral poly-morph of the serpentine group. It is white, yellow or green in color. It is sometimes used as a gemstone.

Magnesite

Magnesite, also known as magnesium carbonate, is a mineral which is colorless, white, pale yellow, pale brown, pink or lilac-rose in color.

Magnetite

Magnetite is an iron oxide mineral which is a member of the spinel group which is black or brownish-black in color. It is the most magnetic of all the naturally occurring metals on Earth. Naturally magnetized magnetite is commonly referred to as lodestone. Magnetite will react with oxygen to produce hematite.

Matulaite

Matulaite is an uncommon secondary mineral which is colorless or white in color.

Microcline, also known as Moonstone

Microcline is a potassium-rich alkali feldspar which is a tectosilicate mineral. It is clear, white, pale yellow, brick-red, or green in color. It is considered a gemstone.

Muscovite, also called Common Mica

Muscovite is a phyllosilicate mineral that can be colored or tinted grey, brown, green, yellow, violet or red; it can also be transparent or translucent.

Nesquehonite

Nesquehonite is a pentahydrate salt mineral that occurs with a whitish color. It is used for fireproofing and other industrial applications.

Nickel

Nickel is a silvery-white colored element with a slight golden tinge that can occur in nature as a free metal. It derives its modern name from a mischievous sprite of German mythology. The symbol for nickel is Ni and its atomic number is 28. Nickel is a corrosion-resistant metal and is used in many industrial applications including the production of rechargeable batteries.

Oligoclase, also known as Moonstone or Sunstone

Oligoclase is a plagioclase feldspar mineral which is usually white in color with shades of grey, green or red. It is considered a gemstone.

Orthoclase, also known as Moonstone

Orthoclase is a tectosilicate mineral which can be colorless, greenish, grayish, yellow, white or pink in color. It is a gemstone which is commonly described in gemology as having a creamy or silvery white appearance.

Pyrite, also called Fool's Gold

Pyrite is an iron sulfide mineral with a pale, brass yellow hue which resembles the appearance of gold. It derives its name from the Greek word for fire due to its ability to produce sparks when struck against steel. It is considered a gemstone by some and has been used in the production of marcasite jewelry. Pyrite has also been used with crystal radios as a crystal detector.

Pyrope

Pyrope is a mineral member of the garnet family, and as such is considered to be a gemstone. It is usually red in color, but can take on a blackish or deep purple appearance.

Rose Quartz

Rose quartz is a type of quartz mineral which is pale pink to rose red in color. It is considered a gemstone by some, but is not in very popular usage in jewelry as it is generally too clouded with impurities for that purpose. Rose quartz is more often used for crafts involving carved figures and shapes.

Sauconite

Sauconite is a phyllosilicate mineral which has a bluish-white to red-brown color. It is a member of the smectite clay group.

Siderite

Siderite is an iron carbonate mineral. It is a pale yellow to tanish, grey, brown, red, green or black color. Siderite can sometimes be found in a colorless form.

Silver

Silver is a lustrous white metallic element. It is considered to be a precious metal. It occurs naturally in a pure free metal form, or as an alloy. The chemical symbol for silver is Ag and its atomic number is 47.

Smoky Quartz

Smoky quartz is a variety of quartz mineral which is grey or translucent in appearance. It is considered a gemstone that can range in color from transparent to a brownish-grey or even black.

Talc

Talc is a hydrated magnesium silicate mineral which is extremely soft and sectile. It has a Mohs hardness of 1, and appears to be white, grey, green, blue or silver in color. Talc has a greasy feel and is the primary component of soapstone. Talc is most easily recognized as talcum powder.

Thorite

Thorite is a silicate minerals which is nearly always extremely radioactive. It is the most common mineral form of thorium. Thorite can be found in yellow-orange, brownish yellow, brownish black or black colors.

Titanite, also called Sphene

Titanite is a calcium titanium nesosilicate mineral which can be reddish brown, grey, yellow, green or red in color. Titanite is often called sphene when it is used as a gemstone.

Uraninite

Uranite is a radioactive and uranium-rich mineral which is more commonly known as pitchblend. It is black or brownish in color and is the main ore of uranium.

Vanadinite

Vanadinite is a mineral of the apatite group of minerals. It is the main industrial ore of the metal vanadium, and has a color ranging from colorless to bright red, orange-red, red-brown, brown, yellow or grey.

Williamsite

Williamsite is a variety of antigorite mineral which is oil-green with black crystals of chromite or magnetite often included. It resembles a fine jade and is sometimes used in jewelry making.

Zircon

Zircon is a mineral in the nesosilicates group with natural color varieties ranging from colorless to yellow-gold, red, brown, blue and green. Yellow zircon is known as hyacinth. It is considered a gemstone, but should not be confused with zirconia or cubic zirconia.

Barnes, J. H., 2004, Rocks and Minerals of Pennsylvania (4^th ed.): Pennsylvania Geological Survey, 4^th ser., Educational Series 1, 30 p.

Barnes, J. H., and Smith, R. C., II, 2001, The Nonfuel Mineral Resources of Pennsylvania: Pennsylvania Geological Survey, 4^th ser., Educational Series 12, 38 p.

Wikipedia, the free encyclopedia

MinDat.org

Minerals.net

Please contact the author of this listing with any additional material, corrections and suggestions.

Gem Trails of Pennsylvania and New Jersey, by Scott Stepanski and Karenne Snow

Earth Treasures Volume 1: The Northeastern Quadrant, by Allan W. Eckert

The Rockhound's Handbook, by James R. Mitchell

Smithsonian Handbooks: Rocks and Minerals, by Chris Pellant

Rocks and Minerals: A Field Guide to Identification, by Charles A. Sorrell

PA DCNR – Pennsylvania Geological Survey

http://www.dcnr.state.pa.us/topogeo/collecting/rocks.aspx

Central PA Rock & Mineral Club

http://www.rockandmineral.org/

Penn Minerals

http://www.pennminerals.com/