Featured News. Greens Sand has been in the silica sand industry since 1979 and has been a distributor of specialised silica sand to the Industrial as well as Leisure market for over 30 years, distributing nationally and across borders. We store a wide range of grades of silica sands.
Standing almost due east of the Reflecting Pool and the Lincoln Memorial, the monument, made of marble, granite, and bluestone gneiss, is both the world's tallest stone structure and the world's tallest obelisk, standing 555 feet 7 11â32 inches (169.351 m) tall.t the time of its completion, it was the tallest building in the world, a title it retained until the Eiffel Tower was completed in 1889; however, the Washington Monument is still the tallest stone structure in the world.
The Washington Monument is a structure called an obelisk, measuring 555 feet and 5 1/8 inches high. According to Wikipedia, an obelisk is: âA tall, four-sided, narrow tapering monument which ends in a pyramid-like shape at the top.