There's hardly a square inch of the 1,900-acre Soldiers Delight Natural Environmental Area that Johnny Johnsson hasn't walked, mapped or studied.
That includes the scant remnants of several 19th-century chromium mines at Soldiers Delight in Owings Mills.
Some of these mines once reached as deep as 200 feet beneath this chromium-bearing geological anomaly, known as a "serpentine barren."
Johnsson, a Finksburg resident who is an environmental engineer by profession — and a mining historian by avocation — has been a volunteer ranger and tour guide at Soldiers Delight, which is part of the Patapsco Valley State Park system, since 1990.
For years, Johnsson has devoted much of his free time ferreting out maps, land deeds, letters and other documents relating the mining history at Soldier's Delight.
"Growing up in Reisterstown, I collected rocks and was aware of Soldiers Delight as a kid," said Johnsson, who by day works in the quarry industry, for Vulcan Materials Co. in Hanover, Pa., specializing in environmental permitting and compliance.
"Then I went away to college and studied mining engineering at Virginia Tech," he said. "After that, I began working in the stone quarry industry and got interested in mining history.
"I did research in Baltimore County land records and the Maryland Hall of Records, the Maryland and Baltimore County historical societies," he said.
His pursuit of records even took him to the Vermont Historical Society, where he studied a hand-written journal of a mine owner. The journal included an account of a visit he made to Soldiers Delight in 1834, and conversations he had with a mine operator there.
In the early 1990s, Johnsson, 49, began volunteering at the Soldiers Delight visitor center, on Deer Park Road, and started leading occasional 2-mile, two-hour history hikes. His educational hikes are based on his extensive research, and he offers them several times a year.
According to Johnsson, the mines at Soldiers Delight, along with others in the Bare Hills district of Baltimore County, were the largest producers of chrome in the world during the 19th century.
Johnsson said the mining industry at Soldiers Delight ebbed and flowed over the years, along with the demand for chromium.
Early on, chromium was used as pigment for yellow paint, and later for munitions.
"The chromium mines at Soldiers Delight date back to the 1820s," he said. "I've tracked down some of the descendants of the owners. And I've researched old deeds and legal cases and found maps and old pictures to document the history of the mines.
One of the mines can still be visited today, even though only traces remain of the others. The entrance to the old Choate Mine is just across Deer Park Road from the Soldiers Delight visitors' center.
"The Choate Mine was opened around 1830 and operated for a while, then shut down," he said. "Then it reopened around the time of the Civil War and operated until about 1880.
"The last time it was reopened was in World War I, when chromium came back in demand for use in armaments," he said.
On his tours, Johnsson shows visitors some of the antique tools and equipment similar to those that would have been used in the Soldiers Delight mines. Visitors also get to pan for chromium.
Johnsson also explains the geological conditions that created Soldiers Delight, which is the largest and most diverse of the few remaining serpentine barrens on the East Coast. The environmental area has been described as a "2,000-acre hunk of the American West dropped into Maryland."
In both ecological and geological terms, Soldiers Delight is unlike any place in the area and is home to 39 rare, threatened, or endangered plant species, along with rare insects, rocks and minerals.
"It's a serpentine barren, so the bedrock is metamorphic rock, called serpentinite," Johnsson said. "It originated when the continents collided and the lower oceanic crust got thrust up on to the continent. And later, when things pulled apart and eroded away, there were pieces of it left.
"And because the rock was of such a deep origin it has some of the heavier stuff in it, like iron, chromium and nickel. So the chromium, which is usually found much deeper in the earth, is nearer the surface here, in this dark, ultramafic rock."
Johnsson will hold his next Soldiers Delight mining tour in spring 2013. The exact date hasn't been determined yet, but will be posted on the Patapsco Valley State Park website calendar of events — http://www.dnr.state.md.us/publiclands/central/soldiersdelight.asp.
Tours begin at the Soldiers Delight Visitor Center, 5100 Deer Park Road, Owings Mills, and are free, though donations are accepted. They are open to anyone age 10 or older.
Advance registration is strongly advised. Those interested can register in person at the visitors' center, or by calling 410-922-3044.
Meanwhile, the visitors' center at Soldiers Delight is open Saturdays, 11 a.m. to 3 p.m., weather permitting, and is also open Sunday through Friday, when staff is available. In the winter months, it's always best to call ahead.
A detailed account of Soldiers Delight's history can be found at: http://home.comcast.net/soldiersdelight/sdci_history.html.