When Capt. John Smith and his crew explored the Chesapeake during summer and fall of 1608, he "fell in with the river Potomac" on the 16th of June and explored the river and its tributaries until the 10th or perhaps 14th of July. Smith's recording of dates was spotty, and in writing of these events in our book, "John Smith's Chesapeake Voyages, 1607-1609," my co-authors and I relied on expert estimates of the elapsed time by Virginia historian Edward Wright Haile.

We thus have a pretty good idea that on or about June 25, Smith's barge made its way to the head of navigation on the Potomac. There, they encountered "divers savages in canoes" coming down from above the fall line of the river "well loade(d) with the flesh of bears, deer and other beasts, whereof we had part" (to supplement their dwindling rations).

Smith's charge from the settlement at Jamestown was dual: Find a water passage to the China Sea (I suspect Smith well knew this was a fool's errand!) and find some gold to keep the Virginia Company investors happy.

At the fall line, Smith found "mighty rocks growing in some places above the ground high as the shrubby trees." Water cascading through the Mather Gorge and Great Falls had eroded the rocks. In the pools and along the banks where the river fanned out and the water slowed into the tidal estuary, the explorers found sediment deposits, some of which were "spangled scurf that made many bare places seem as gilded."

They found these deposits to be a fine clay in which were mingled tiny yellow spangles as if —Smith, eschewing to say "gold" — it had been half pin dust." (In Smith's time and into the 19th century, the hand-grinding to put points on common straight pins resulted in extremely fine particles of brass called pindust.)

This was probably the yellow color of iron pyrite, called "fool's gold" throughout the U.S. West, but it must have raised their expectations. After local Indians told them of "mines" not far down the Potomac where the Powhatan peoples gathered to trade a highly valued mineral they called "matchequeon," it took Smith only a few days — about July 2, 1608 — to find the site.

Capt. Christopher Newport had traded for small bags of this stuff at Jamestown and told Smith before his exploration that he'd sent samples to London and it had turned out to be "half silver."

The Smith account continued: "The King of Patawomeke gave us guides to conduct us up a little river called Aquia Creek, up which we rowed as high as we could." Afoot, with their guides (who were more likely hostages than guides and were chained to prevent them carrying out the harm ordered by the distant Paramount Chief Powhatan) Smith and crew found the "mines" which apparently contained flakes of mica, and not silver. Obedient to Newport's orders, they nonetheless carried large amounts of it back to the barge (about seven or eight miles) for later assay in England. When the analyses were completed much later, no silver was found.

Ironically, gold was discovered many years later in this region, which became Stafford County, VA. As much of 5,000 ounces a year (valued at $7.8 million at 2012 prices) were mined there into the 20th century.

The barge headed back down the Aquia and into the Potomac, passing right by outcrops of sandstone that would, in a century of so, be a mineral resource that would become a dominant face for Washington, DC, architecture.

The tidewater Chesapeake, by and large, is without rocks. Only at the fall line of major rivers and in one case at and near the estuarine mouth of the Patapsco do rocks emerge significantly from the landscape. They are the ancient underpinnings of the region's Cretaceous past; ancient outcrops of what geologists describe as arkosic sandstone.

Along Aquia Creek, on what once was called Wiggington's Island, stood a huge deposit of solid sandstone. It's not clear if the man, William Wiggington, ever lived on the island, but he was residing along the creek, where a band of marauding Indians from Maryland murdered his wife and three children.

The site was subsequently sold to others, then in 1694 to George Brent, nephew of Col. Giles Brent, and his sister Margaret Brent. Their name rode with the island for nearly a hundred years. The Brents had been in Virginia for decades and were equally well-known in Maryland.

Margaret Brent was noted for her appearance before Maryland's Provincial Assembly at St. Mary's, boldly claiming two votes, one as a landowner and second as designated executor for the deceased Leonard Calvert. Leaving that legacy, some claim "as the first suffragette," Margaret was denied that recognition and joined her brother Giles in Virginia. Giles married a Maryland Indian woman, the "Princess" Mary Kittimaquund. History records she was 10 or 11 at the time.

They established a quarry at Aquia, providing tombstones and construction block for area buildings. On the island, existing beds of Aquia freestone were 60 feet deep, with finer textured stone in higher deposits and coarser grades deeper. Freestone is often tan, sometimes brownish or gray, sometimes reddish striped. When freshly excavated it is relatively easy to work. Later, It was often whitewashed, a treatment which protected it against weathering. Examples in construction have survived at least two centuries.

George Washington, virtually a neighbor to Aquia, obtained stone there for the steps at Mount Vernon. His home, meanwhile, was faced with beveled wood panels that were coated with paint textured with sand, making them look like Aquia freestone.

The commissioners who developed the territory of "Columbia" selected Aquia freestone as the logical material for the government buildings envisioned for the nation's new capital.

To secure this supply, Pierre Charles L'Enfant bought Brent's operation on behalf of the people of the United States in 1791, after which it became known as "Government Island." He had title to the whole thing save one acre where Robert Steuart had a wharf or landing with very deep water, suitable for the shipment of heavy barges laden with stone.

Also in 1791–92, Maj. Andrew Ellicott, a noted surveyor, and Benjamin Banneker, an African American polymath, directed the surveying of today's familiar District of Columbia diamond shape, to encompass 100 square miles — 10 miles on a side. They marked the boundary with 40 engraved blocks of Aquia Freestone, each topped with a truncated pyramid. This was quite a task in what was still undeveloped wilderness, requiring lines of sight to be cleared and much slogging through the marshes and streams that once laced the area.

The stone was quarried by teams of men, enslaved and free, by cutting deep paths just wide enough for a man through solid rock to separate masses of stone. Deep grooves were cut laterally using picks. Then, horizontal slots just a couple of inches wide, were picked out, into which iron wedges were driven with sledge hammers. Finally, blocks of freestone weighing many tons cracked free and could be slid out on sledges and hauled down to waiting barges or schooners.

The stone sent the 40-odd miles up to Washington was rough cut, and men working in sheds or tented open yards in the city dressed the stone, turning some into straight, fluted columns and others into wonderfully carved interior decoration. The the finest textured stone was reserved for sculpture.

George Washington repeatedly visited the construction site for the "President's House," which he called "my building," and witnessed its progress with pleasure. He visited the last time on Nov. 9, 1799. He died Dec. 14, before there was any chance it could be occupied.

President John Adams and his wife, Abigail, were the first residents. Abigail wrote about what hard living they had in unfinished quarters, especially in severe winter cold. She made the best of it, knowing that the structure was destined for the future of the United States. "The President's House is in a beautiful situation in front of which is the Potomac with a view of Alexandra." Describing one of modern Washington's toniest neighborhoods, she wrote, "I have been to George Town…it is the very dirtiest Hole I ever saw for a place of any trade or respectability of inhabitants…a quagmire after every rain."

Freestone was literally the backbone of the city's public buildings — notably the White House and the U.S. Capitol. Both were burnt and the stone extensively pitted during the British attack in 1814. They were rapidly cooled by a thunderstorm that saved both from complete destruction. After extensive repair, both buildings were whitewashed and painted to forestall weathering that progressed over the decades.

Other major public structures of Aquia freestone include the Old Patent Office, U.S. Department of the Treasury and the Pilgrim Steps of 1893, which lead to the National Cathedral. Freestone is integral to many other structures and monuments in the District.

The late Chesapeake maritime historian, Arthur Pierce Middleton, helped me greatly in my early studies of Chesapeake history. As time passed I learned many things about his personal history. "Did I ever tell you," he once said, "that my father invested in a quarry down the Potomac?" He added that not all of the Aquia Freestone outcrops were on Government Island, and other quarries had been opened in the Aquia basin — and elsewhere at the fall line

One pair of quarries, the Rock Rimmon and (just downstream) the Mount Pleasant, were purchase in 1922 by Arthur Middleton, Pierce's father. Middleton's ancestor (from South Carolina) was one of 56 signers on the Declaration of Independence and perhaps in honor of this, he incorporated his firm as The George Washington Stone Corp. He spent $64,000 on steam-powered equipment, roads and a rail system to move the rough-cut stone. The engine was an adaptation of an old roadwork steamroller, which apparently did well in its new life. Other investors joined the project as tugs and barges were acquired amidst the ebullient economic expectations of the Roaring 1920s.

Marketing changed the name of the product from Aquia, to "Colonial Freestone" and it again became quite a popular building material. Pierce Middleton showed me one of the brochures which he'd saved, much like those which hawk products today. Dr. Howard Kelly, a major investor in the project, wrote in 1926 that his son, Henry, who worked there "has his life work marked out for him on congenial lines."

The stock market crash in 1929 and the subsequent Great Depression caused stonecutting to grind to a halt on the Aquia. The quarries have since been abandoned and massively overgrown. Trees now almost three-quarters of a century old obscure many of the once stark industrial vistas.

In 2011, Dave Davis visited the site and thoroughly explored it with several of Dr. Kelly's descendants. It's to him and Jane Conner's wonderful book, "Birthstone of the White House and Capitol," that I owe much of this Prologue column.

When Ellicott's crews surveyed the diamond-shaped boundary of the original District of Columbia in 1791 and 1792, the 40 carved blocks of Aquia freestone weighing about a half ton each seemed to be permanent.

Over the centuries, though, a number have suffered various indignities: One was damaged by a farmer's plow, another was used for target practice during the Civil War, and a third, stranded on a too-narrow highway median strip, was struck and broken by a wayward automobile in the 1960s. The greatest indignity occurred when the stone was broken by a bulldozer clearing the land for a strip mall.

Thirty seven of the stones remain, and when part of the original District territory was returned to Virginia in 1847, some of them ended up on private property, where advocates are still trying to assure their permanent preservation.

Viewing the nation's Capitol as an Aquia Freestone structure is deceptive — only about 60 percent of the original stone remains.

At the National Arboretum in Northeast DC, the "Capitol Columns" are fashioned from Aquia. When I first saw them, they were scattered about the ground like Greek ruins. Today they are erect, and I think today's configuration is quite stunning. Visitors can walk around them, touch and admire the original stuff at its best.