Pennsylvania may not be the first place that comes to mind when thinking of gemstone mining, but the Keystone State has a surprising diversity of beautiful natural gemstones that can be found across its varied landscapes. From sparkling quartz crystals to rare garnets, exploring Pennsylvania's outdoors reveals a treasure trove of unique gems waiting to be discovered.
Quartz is one of the most common minerals on Earth and can be found in abundance across Pennsylvania. Large quartz crystal clusters, doubly terminated points, and drusy quartz coatings are located in areas like the crystalline limestone deposits of southeastern Pennsylvania. Clear quartz, milky quartz, smoky quartz, and rose quartz varieties are widespread. Significant quartz deposits occur near Crystal Cave in Kutztown, where glittering druse and dogtooth spar crystals line the underground cave walls. The fluorescent mineral properties of quartz can be viewed under UV lights at night.
Calcite calcium carbonate crystals are another very common mineral found across the state. Translucent Iceland spar and massive white calcite formations occur in limestone caves and mines in places like Cumberland, Snyder, and Lehigh Counties. The most famous calcite crystals in Pennsylvania come from the Elizabeth Copper Mines in Lancaster County. Beautiful scalenohedral calcite crystals up to 20 centimeters long once lined the mine walls. Small bright orange calcite crystals have also been found coating geodes in the Triassic shales of the Gettysburg Basin.
Pennsylvania has a diversity of garnet varieties that can be found embedded in schist, gneiss, and pegmatite deposits across the state. In Southeastern Pennsylvania, almandine garnets up to several centimeters wide give the hornblende-garnet schist a dark reddish color. Smaller pyrope garnets can sometimes be found associated with chromite in serpentinite rock. Andradite garnets have been found in skarn deposits in Cornwall, Lebanon County. Fine demantoid andradite garnets, though very rare, have been discovered in serpentinites around Ridley Creek State Park.
Beryl family gemstones like emerald, aquamarine, morganite, and heliodor can uncommonly be found in Pennsylvania's pegmatite deposits. Aquamarine's light blue color comes from traces of iron, while emerald's signature green results from chromium. Mostly opaque yellowish-green beryls have been found in pegmatites near Avondale in Chester County. Clear light blue aquamarine crystals were discovered in pegmatite near Birdboro, Berks County. Higher quality emerald specimens have been unearthed near New London in Chester County.
Tourmaline is a boron silicate mineral that displays a wide range of colors. In Pennsylvania, black schorl tourmaline is the most common type found, especially in pegmatite deposits across the southeast. Nearby localities in Newlin Township, Chester County contain schorl tourmaline crystals up to 10 centimeters long. Multicolored watermelon tourmaline displaying pink and green zones has rarely been found in the state as well. Notable tourmaline localities include quarries near Media in Delaware County.
Fluorite is calcium fluoride that often forms in cubic crystals and can display a range of vivid colors. In Pennsylvania, fluorite is found in deposits of limestone and dolostone in the central and western parts of the state. Green, yellow, blue, purple and colorless fluorite is found in association with metallic mineral deposits around New Florence, Westmoreland County. Large cubic fluorite crystals up to 5 centimeters across have been mined from sites like the Hedgehog Mine in Clay Township and the Harris and Arista Mines in Butler County.
Amethyst is the rare purple variety of crystalline quartz, colored by traces of iron. Significant deposits of amethyst have been found in Pennsylvania's Triassic Basin red shale and basalt rock, particularly around Gettysburg. The hills along the Pennsylvania-Maryland border contain fractured basalt rock that allows quartz-bearing solutions to crystallize in cracks, forming amethyst vugs and geodes. These vibrant purple quartz crystals can often be found lined inside holes weathered into the fractured basalts. High quality clusters have been collected from sites near Arendtsville and Biglerville.
Sphalerite is zinc sulfide that forms in tetrahedral crystals and comes in black, brown, yellow, orange and reddish varieties. It is mostly found near old zinc mines across Pennsylvania which were once a major producer of this ore mineral. Translucent brown "resinophene" sphalerite crystals up to several centimeters wide were notably collected at the Friedensville Zinc Mine near Orefield in Lehigh County. Cleophane is a colorless and transparent variety also found in the state. Fluorescent sphalerite specimens can be hunted in Franklin, Somerset and Berks Counties.
Pennsylvania's diverse geology has created ideal conditions for a wide variety of natural gemstones to form across the state. Exploring the unique outdoors reveals quartz, calcite, garnet and more - hidden gems waiting to be uncovered by avid rockhounds and gem lovers seeking adventure. The thrill of discovering your own crystals or gemstones as beautiful as ones from any store is an experience unmatched. Whether mining an old quarry, hiking through the mountains, or picking through a stream bed, Pennsylvania's scenic landscapes hold untold treasures beneath the surface for those willing to search.
