***PLEASE READ THIS BEFORE BEGINNING THIS EC***
This is a D3.5 EC with the expectation that time is spent both considering and providing answers to the questions. In other words, a 1 word / brief response will not suffice. Thank you.
There is no admission charge to visit / tour the Colorado State Capitol Building.
The Capitol is open Monday-Friday, 7:30-5:00. Free guided tours are available Monday-Friday on the hour between 10:00am-2:00pm. The Visitor Information Desk is open Monday-Friday, 9:00-3:00. Visitors are welcome to do a self-guided tour of the public-access spaces (see bullet points below). Please refer to the website regarding holiday and other closures.
Two entrances are available for Capitol visitors. You may enter the building on the north side (Colfax and Sherman Avenues), up the stairs, or use the ADA accessible ground level entrance (14th and Sherman Avenues), under the stairs.
This EC was created ("placed") with permission from the Capitol Building Visitor Services and Facilities teams. As such, please respect the following rules:
- Visit only during the published opening hours;
- NO (mass) group caching (the free guided tours can accommodate up to 30 individuals; however, I would ask that you keep group caching to <5 people if you are doing a self-guided tour);
- Like all visitors to the Capitol, expect to pass through security screening when entering the building;
- Those participating in the geocaching lesson are permitted in the common areas of the Capitol and Mr. Brown's Attic Museum, and the dome (you will only have access to the dome if you are signed up and able to take the entire Capitol tour - approximately 1 hour);
- Please note: this EC is based on the common areas of the Capitol and will not require a visit to Mr. Brown's Attic Museum or the dome;
- Leave no trace of your visit.
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Rose Onyx
The interior of the capitol was built with the rare and priceless Colorado Rose Onyx. The mauve marble is so rare that its known supply was completely used up in the process of beautifying the Capitol.
There is much to dazzle the eyes in the Colorado State Capitol — intricate stained glass, towering columns, gilded crown molding, gleaming brass chandeliers and, of course, the gold dome atop it all. Surprisingly, one of the building’s most striking features is one you can walk right up to and touch.
From the moment you enter the capitol building, you’ll notice a pinkish, marble-like stone that comprises the tall wainscoting and column plinths. The rich rose, blush and crimson hues are not unlike that of late-summer Colorado sunset. And if you look long enough at the rock’s swirling veins, you’ll begin to see shapes, designs and figures in the grain — here a woman’s profile, there a rippling pond, here a mountainous landscape.
What is this unusual material? It’s no exaggeration to say it is one of the rarest stones in the world. Once called Beulah red marble, the stone is actually not marble, but rather is metamorphosed limestone tinged with iron oxide. Also referred to as Colorado rose onyx, the stone was discovered in a small deposit in the town of Beulah (near Pueblo, Colo.) in 1893. The Beulah quarry remains the only known source of the stone in the world.
In fact, the adornment of the Colorado State Capitol’s interior depleted the entire known supply of rose onyx.
Tour guide Aaron Fennimore notes that a reserve supply of the quarried rose onyx is kept in the capitol’s underground vaults but is rarely used. “Twice I’ve seen the rose onyx break, but the restoration team was so skilled in repairing it that you would never even know the damage was there,” he says.
Mining and Geological History:
The quarries are located 1.5 miles west of Beulah at the edge of a small canyon, and are largely invisible until reaching the quarry edge. Three main quarries supplied most of the production, but three smaller quarries with limited production have also been identified. The quarries are remarkably small when considering the amount of marble in the capitol and the large amount of waste rock generated.
The Beulah Marble story starts and ends with the Colorado State Capitol. “Fine quality marble” at Beulah was first mentioned in the print in 1890, but was not of commercial interest until January of 1894 when the exterior work on the capitol was completed and work began on the interior. The Colorado legislature mandated that all capitol construction materials come from within the state, and the capitol management committee invited interested bidders to submit polished samples of Colorado marble in competition for a $300,000 (roughly $22 million today) contract for the interior marble. Samples were submitted from Beulah, Canon City, Cotopaxi, and Marble.
The quarry geology is more complex than most marble deposits, forming from a paleokarst process that occurred over 300 million years ago. In geologic terms, the Beulah Marble is not technically a marble, which is a limestone that has been recrystallized by heat and pressure but fits the commercial term of marble of being any limestone that will take a polish and can be used as an ornamental stone.
Beulah marble is geologically a liesegang-banded limestone with the multi-stage banding formed by repeated groundwater deposition of hematite. The paleokarst process involved limestone erosion and dissolution prior to deposition of the overlying strata, sinkhole and cavern formation followed by infilling with iron-rich sediment, followed by iron leaching out into the surrounding limestone to form the marble. The marble only occurs around the infilled caverns and sinkholes, explaining why the deposits were small, discontinuous, and difficult to mine. Because of the complexity of the formation process, no other similar occurrence is known outside of Beulah, although paleokarst hosts numerous mineral deposits in Colorado and throughout the country. Each quarry produced a slightly different type of marble, and polished slabs in the capitol can be matched to the corresponding quarry.
The quarries have been idle since 1900, and the only equipment remaining is one derrick used to lift the marble out of the quarry. The property was purchased in 2017 with the desire to preserve it from future development and maintain it as an undisturbed historical site.
Yule Marble
The floors of the capitol are tiled in white Yule marble, the state rock of Colorado. The stone was quarried in Marble, Colo. “It is one of the purest and densest marbles in the world,” Fennimore says.
Yule Marble is a marble of metamorphosed Leadville Limestone found only in the Yule Creek Valley, in the West Elk Mountains of Colorado, 2.8 miles (4.5 km) southeast of the town of Marble, Colorado. First discovered in 1873, it is quarried underground at an elevation of 9,300 feet (2,800 m) above sea level—in contrast to most marble, which is quarried from an open pit and at much lower elevations.
The localized geology created a marble that is 99.5% pure calcite, with a grain structure that gives a smooth texture, a homogeneous look, and a luminous surface. It is these qualities for which it was selected to clad the exterior of the Lincoln Memorial and a variety of other buildings throughout the US, in spite of being more expensive than other marbles. The size of the deposits enables large blocks to be quarried, which is why the marble for the Tomb of the Unknown Solidier at Arlington National Cemetery, with its 56-long-ton (57 t) die block, was quarried from Yule Marble.
The forces that created Yule Marble make it distinct from all other American marbles. Instead of being formed through regional metamorphism (a process more closely related to mountain building and erosional processes), it was formed by contact metamorphism. Contact metamorphism occurs typically around intrusive igneous rocks as a result of the temperature increase caused by the intrusion of magma into cooler country rock. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole, the contact aureole, or simply the aureole. Contact metamorphic rocks are usually known as hornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained and extremely tough.
Yule's quality comes at a high price due to the cost of quarrying in a high-altitude mountain environment. This challenge has caused the industry and the town of Marble to undergo many boom-and-bust periods since quarrying started in the mid-1880s, making the town emblematic of the economic fluctuations that beset a single-industry economy. Technology advancements in quarrying machinery and transportation have reduced, but not solved, the cost problem that afflicts the operation through the present.
Sources:
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Questions - if you are delayed in sending your responses, please post a write note (and not a find). If sending responses for more than one cacher, clearly indicate the cachers' names in your submission; regardless, EACH cacher must post their own unique photo at GZ.
1. Required photo - looking at the rose onyx, find a "shape" (i.e. a woman's face, mountain, etc) and post a photo of you/another identifying object with your log. EACH person in your group must post their own unique photo.
2. Based on the lesson, the examples of liesegang-banding provided (photos) and your observations, describe, compare and contrast the liesegang-banding present in the rose onyx to the banding illustrated in the photos provided.
3. In what ways is the liesegang-banding pattern in the rose onyx reflective of its geological formation?
4. Identify where in the building Yule marble is primarily used. Explain why the architects made this decision, connecting your answer to the unique geological formation of Yule marble.
5. They used all of the available rose onyx in the world to decorate the Capitol, but no one knows EXACTLY how much rose onyx was used. We're going to try and figure it out!
Based on your observations, and using the following information, estimate the total amount of rose onyx that comprises the base of one of the column plinths in the Capitol.
We will measure using the metric system (i.e. kg), but you can calculate or convert and submit your final answer using Imperial (i.e. lbs). The formulas remain the same, only the units of measure differ (i.e. use metres/feet; kg/lbs).
- Calculate the volume (m3) of the rose onyx that "plates" the plinth = length x width x height
- A cubic metre of pure water has a mass of 1000 kg, or one tonne
- Specific gravity of onyx is 2.55-2.7
- Specific gravity is a relative measure of density ... so onyx is 2.55 x more dense than water
- Calculate the density of the rose onyx (kg/m3) using the information in the proceeding bullet points
- Now, using your calculations, find the Weight (kg) = volume x density
- If you want to, convert to cubic feet using the following formula: 1 kg = 2.20462 lbs
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I will read and reply to all responses. Enjoy this gorgeous location!