Rockhounding Map & Sites in Maryland: 77 Locations for Crystal Hunting, Gem Mining & More

Calvert Cliffs along the western shore of the Chesapeake Bay is one of the premier fossil collecting sites on the East Coast. The Miocene-age Calvert and Choptank formations (10-20 million years old) contain an extraordinary concentration of fossil shark teeth, whale bones, dolphin remains, and marine invertebrates. The fossils erode from the cliffs and wash onto the beach with each storm and tidal cycle.

Top sites:

• Calvert Cliffs State Park, Calvert County — 1.8-mile trail to the beach. Collecting is allowed from the beach only — do not dig into or climb the cliffs (unstable and prohibited). Free with state park admission. Sedan access to parking lot. No tools needed — pick teeth from the sand and gravel at the waterline.
• Flag Ponds Nature Park, Calvert County — County-operated park with beach access to the same Miocene formations. Seasonal hours; entrance fee. Shorter walk to the beach than Calvert Cliffs State Park.
• Brownies Beach (Bay Front Park), Calvert County — Public beach access. Same Miocene fossil-bearing strata. Less crowded than the state park.

Common finds are teeth from sand tiger sharks, makos, snaggletooth sharks, and cow sharks, ranging from 1/4 inch to 2 inches. Megalodon teeth are rare but present — look for large triangular shapes with serrated edges in dark brown to gray. Best collecting follows storms that erode fresh material from the cliffs. Bring a mesh screen to sift gravel at the waterline.

Maryland has a belt of serpentinite — metamorphosed ultramafic rock — running through the Piedmont Plateau from the Pennsylvania border to near Washington, D.C. This rock formed from ancient oceanic mantle material thrust onto the continental margin during the closing of the Iapetus Ocean roughly 450 million years ago. Serpentinite weathers into distinctive barren areas called "serpentine barrens" with rare endemic plants and unusual mineralogy.

Top sites:

• Soldiers Delight Natural Environment Area, Baltimore County — State-managed land. Open to hiking; mineral collecting is restricted — check with the Maryland Department of Natural Resources before removing material. Chromite, magnetite, and deweylite occur in the serpentinite. Sedan access to parking areas.
• Bare Hills, Baltimore County — Historic chromite mining district. The Bare Hills serpentinite body was mined for chromium in the 1800s. Old prospects and mine dumps on mixed public and private land. Some surface collecting possible — verify land status before digging.

Serpentinite is dark green to black, waxy to greasy in feel, and soft (hardness 2.5-4). Associated minerals include chromite (black, heavy, metallic), magnetite (responds to a magnet), and chrysotile asbestos (fibrous — do not disturb or inhale fibers). A hand lens and magnet help with field identification. Chromite is the primary ore of chromium, and Maryland was the nation's first chromite producer in the early 1800s.

The Maryland Piedmont — the metamorphic belt between the Coastal Plain and the Blue Ridge — produces almandine garnet in mica schist and gneiss. These garnets formed under regional metamorphism during the Taconic and Alleghenian orogenies (450-300 million years ago) as aluminum-rich sediments recrystallized under heat and pressure. The crystals range from sub-millimeter grains to specimens over 1 inch in diameter.

Top sites:

• Marriottsville area, Howard County — Road cuts and stream exposures along the Patapsco River valley expose garnet-bearing mica schist. Garnets weather out of the schist and accumulate in stream gravels. Surface collecting from public road shoulders and stream banks. Sedan access.
• Woodstock area, Howard and Baltimore counties — Similar Piedmont metamorphic terrain with garnet schist exposures along road cuts on Route 99 and in railroad cuts. Check land ownership — much of this area is private.

Maryland almandine garnets are dark red to reddish-brown, typically forming dodecahedral or trapezohedral crystals embedded in silvery mica schist. Look for the characteristic "bumpy" texture on schist outcrop surfaces where individual garnet crystals resist weathering and stand proud of the softer mica. A rock hammer and chisel free matrix specimens. For loose crystals, screen stream gravel from creeks draining the schist — garnets concentrate in heavy mineral deposits on the inside bends.