This Earthcache is located within the Washington State Capitol Building, also known as the Legislative Building. Access is limited to the following times:
Monday - Friday: 7:30 a.m. to 5:00 p.m.
Saturday & Sunday: 11:00 a.m. to 4:00 p.m.
Holidays: 11:00 a.m. to 4:00 p.m.
Closed: Thanksgiving Day, the day after Thanksgiving, Christmas Day, and New Year’s Day
Washington State’s Capitol Building was completed in 1928 after six years of construction, and serves as both a working governmental center and a symbol of Washington’s free and democratic government. The building is comprised of more than 173 million pounds of stone, brick, concrete, and steel. It is one of the tallest masonry dome in the world and the tallest in North America, rising 287 feet high.
Much of the Capitol Building's interior is decorated with natural marble:
Marble is a compact metamorphic rock, formed from limestone that has been subjected to high temperature and pressure, resulting in a high degree of crystallization. All metamorphic rock begins as one type of rock, and is then transformed. Before marble becomes marble, it is first limestone formed on the shores and floors of tropical seas. Limestone is an accumulation of shells and shelly fragments which are made of the mineral calcite. Depending on the conditions at a particular beach or sea, limestone’s shelly sediment may be punctuated with occasional layers of clay or lenses of sand.
The heat and pressure necessary for the formation of marble typically occur deep within the Earth’s crust. When a limestone seabed gets dragged down due to tectonic movements, the additional heat transforms the calcite grains and fuses them together tightly. The dynamic action of rock layers as they become buried, twisted, and shoved around causes the original flat layers to bend, buckle, and swirl together. A rock in this heated state doesn’t melt, but is warm and flexible. This process of heating and warping is responsible for marble’s trademark aesthetic of gracefully flowing bands of color.
Monocolored marbles: Marbles of a single color, such as white, cream, red, pink, black, or yellow.
Polychrome marbles: Marbles made up of several colors with veins or fragments.
Marble is mainly composed of calcium carbonate in the form of low-pressure, hexagonal calcite. Impurities, or foreign substances, also find their way in during the metamorphic process. These impurities play a significant role in determining the color and physical characteristics of the marble. Some common impurities include iron oxides, graphite, clay, serpentine, sulfides, quartz, mica, and feldspar.
Marble can take on a large range of hues and textures, but most marble is white. Solid white marble is pure calcite, without intervening minerals to add color.
Iron oxide impurities can give marble various shades of red, pink, brown, yellow, and orange. Hematite creates reds and yellows, while limonite produces browns and yellows.
The presence of graphite in marble can result in a steely gray color with metallic glimmer. Fossil-rich limestone becomes graphite-infused marble. As the rock is heated, the fossil carbon reverts back to the elemental carbon in graphite.
Clay minerals introduce earthy tones such as beige, tan, or brown to the marble.
Serpentine impurities, rich in magnesium, create green or deep red marble.
Minerals such as lazulite can result in vibrant blues. Porphyry deposits can create a violet coloring.
Sulfides and organic materials can lead to black or dark veining in the marble.
A marble breccia is formed when the stone fractures underground. This often happens to stones present in a fault zone. Mineral-laden groundwater fills in the voids and patches the fragments back into a solid mass, while creating a spectacular pattern at the same time.
To log this Earthcache:
Visit at least one of the many locations within the Capitol Building that displays marble. Select one square foot section of marble you would like to examine, and complete the following tasks.
Include a picture in your log of yourself or a personal item at the sample location, and send me the answers to the following questions:
1. Describe the color and pattern of the marble sample.
a. Is it monocolored or polychrome marble?
b. Does it display any fragmenting, veining, or breccia patterning?
2. Describe the possible mineral impurities and geological processes that helped form this particular sample of marble.
References
Breche Violette. Marc Maison. https://www.marcmaison.com/architectural-antiques-resources /breche_violette_marble?fbclid=IwAR3n1-2el9Fni-AAS3jJyKetdq3BhzXKJG7zk0ylN9ZveXao PG9FggyR0mk_aem_AXlqm7UPIbKMrCodIyVOrmYhEtOSTYMkNfqMYLbkZOU_FRdZYW4PRD USHpJjtYZmDxYZmNX5dWA4NRjeReTobwQF
Capitol Facts & History. Washington State Department of Enterprise Services. https://des.wa.gov/services/facilities-and-leasing-management/capitol-campus/buildings/legislative-building/capitol-facts-history
Definition of Formosa Marble. Mindat.org. https://www.mindat.org/glossary/formosa_marble?fbclid=IwAR1W2FRsPuYjyMTiaQpEBVimOkxoY3HVTI2--uAQhsuYMWhPTJy8WjpKCCk_aem_AXnZ23XszczzQOFyzysJ_WiY_xdxvdNKeBVe_ZgjHDjDMk1Vf5yKEReLt-HLLes6mP_HrbBQ8QARS2Y_bGghvw7P
Escalettes Marble. StoneContact.com. https://wap.stonecontact.com/escalettes-marble/s11158?fbclid=IwAR2R6FggcDUW-E-6X74NyRBiYDhe_mZJRa1suegOevu0JCEi2-iHBR1hWhs_aem_AXmJENbsEr5qSwKJcEKeK4t_O_GSKt6J2o_gcQQiz3AeQNwR_ZH_ccw-zy3EcFqL8nKo1dnyWEenY2ylzds0qqcg
Mad About Marble: A Geological Look at a Classic Stone. Use Natural Stone. https://usenaturalstone.org/mad-marble-geological-look-classic-stone/
Marble Colors. Dedaldo. https://www.dedalostone.com/en/tag-mat/marble-colors/#:~:text=What%20color%20is%20marble%3F,the%20many%20chromatic%20varieties%20available.
Red, White, and Blue: Where Does Marble Get It's Color? Boston Stone Restoration. https://bostonstonerestoration.com/red-white-and-blue-where-does-marble-get-its-color/?fbclid=IwAR1uz3vVjv3F8EqlSAO3PsLI8ZTHs0Uuo6Oy_QdbkArmw_USLWMD1xzQ9yY _aem_AXkqbKPIf9Opj2d9gf1zx7hK3NLxm45RSTjBC_RvrRa2gXxQjoQq76b0D3AkEJ5lfad T10nO3S78lKN7eR_BjRXK
Types of Marbles. Pulycort. https://www.pulycort.com/en/marbles/types-of-marbles.html
Types of Marbles. Tina. https://www.tinostone.com/types-of-marble/
Washington State Capitol. Wikipedia. https://en.m.wikipedia.org/wiki/Washington_State_Capitol