Like other sandstones, brownstone is a sedimentary rock that is formed from eroded quartz and feldspar. Typically silica or calcium carbonate act as a cementing materials to hold the grains of quartz and feldspar sand together. Iron oxide may give the sandstone a red color and manganese imparts a purple hue to the sandstone.
Sandstones form from older rocks (granite and gneiss) which get weathered and break down into sand-sized sediments. The quartz and feldspar grains from the granite and gneiss were transported and deposited by water or wind into areas where they accumulate and begin the process of lithification or sedimentary rock formation. The sand grains that eroded from those older rocks contained metals that are often not oxidized. After the sands were deposited, ground water containing dissolved oxygen moved through pore spaces between the grains of sand. The oxygen in the water removes electrons from the metals to produce rust-like oxides like ferric iron oxides, manganese oxides and aluminum oxides. Each of these metal oxides imparts a unique color to the sandstone.
Brownstone, like other sandstones has a medium density of about 2.5 grams per cubic centimeter.
Wikipedia identifies some types of brownstone - http://en.wikipedia.org/wiki/Brownstone
Apostle Island brownstone
In the 19th century, Basswood Island, Wisconsin, was the site of a quarry run by the Bass Island Brownstone Company which operated from 1868 into the 1890s. The brownstone from this and other Apostle Islands quarries was in great demand, and brownstone from Basswood Island was used in the construction of the first Milwaukee County Courthouse in the 1860s.
Hummelstown brownstone
Hummelstown brownstone is extremely popular along the East Coast of the United States of America, with numerous government buildings from West Virginia, Pennsylvania, New York, Maryland, and Delaware being faced entirely with the stone. The stone comes from the Hummelstown Quarry in Hummelstown, Pennsylvania, a small town outside of Harrisburg, Pennsylvania. The Hummelstown Quarry is the largest provider of brownstone on the east coast. Typically the stone was transported out of Hummelstown through the Brownstone and Middletown Railroad or taken by truck up to the Erie Canal.
Portland brownstone
Portland brownstone is also very popular. The stone from quarries located in Portland, Connecticut and other nearby localities was used in a number of landmark buildings in Chicago, Boston, New York City, Philadelphia, New Haven, Connecticut, and Hartford, Connecticut.
New Jersey brownstone
At Rutgers University, Old Queen's, built 1809–1823, was constructed from ashlar brownstone quarried in the hills near New Brunswick, New Jersey.
Quarries from the Passaic Formation in northern New Jersey once supplied most of the brownstone used in New York City and in New Jersey itself.
South Wales Brownstones
Devonian aged Sandstones commonly used in building stones in South Wales, The United Kingdom.
To claim credit for this Earthcache please send your answers to a cache owner for the following questions:
- Based on the descriptions above, what type of brownstone makes up the construction of the church at the posted coordinates?
- Which metal oxides do you think are found in the brownstone making up the church?
- Measure the stone on the corner of the church near the posted coordinates that has the name of the church and the date of construction. Assume that the stone is 25 centimeters thick. Use the density of 2.5 grams per cubic centimeter to estimate the mass of the stone in kilograms.
Special thanks to ScienceCacher for creating this Earthcache.