Tasks:
Obtain a piece of rock from within the quarry. Scratch the rock using a nail, knife or something else hard enough to create a small pile of powder. Add a few drops of vinegar to this powder pile. Answer the questions below after observing what happens next.
1. Does effervescing occur?
2. If effervescing occurs (or not), what does this tell you as to the type of rock that you have selected?
3. One way or the other (yes or no as to question #3), explain why this is.
4. What type of kiln is found at the coordinates?
5. The finished product, lime, was also called ____?
6. What would excessive cooking heat produce?
Limestone Formation:
During the Silurian period the Earth entered into a long period of global warming. Melting of large glacial formations worldwide caused a shallow, warm, salt-water sea to develop and cover the central portion of the North American continent. Marine life such as brachiopods, crinoids, stromatoporoids, trilobites, conodonts, corals and many other creatures inhabited this vast inland sea. As time passed, the sea bottom became covered with the skeletal remains (Calcium Carbonate) of these ancient marine creatures. This sediment, under pressure, heat and time, eventually solidified and altered into a porous stratum called Limestone. This process is known as Lithification. Limestone is ordinarily white but impurities such as Iron Oxide make it appear cream, gray, yellow or beige. Carbon (Iron) particles give it a blue or black hue. On the Mohs scale of hardness, Limestone/Calcite is a 3. Limestone makes up about 10% of the total volume of all sedimentary rocks found worldwide.
Dolomite Formation:
Dolomite forms after Limestone has already gone through the process of Lithification. When Magnesium-rich water precipitates through Limestone, Magnesium Carbonate replaces the Calcium Carbonate within the upper layers of the Limestone. This process of replacement is called Dolomitization. Dolomite, being harder than Limestone, is used as ornamental stone, as a concrete aggregate and as a source of Magnesium Oxide, a refractory material. Dolomite is generally white, gray or pink in color. On the Mohs scale of hardness, Dolomite/Magnesium Carbonate is a 3.5/4.
Calcite:
Calcite reacts very strongly (effervesces) when mixed with an acid. Limestone, being mainly composed of calcite (calcium carbonate), should react with enthusiasm. Impurities contained within limestone can cause this reaction to be less severe. Dolomite (Magnesium Carbonate) reacts with acid much less vigorously, if at all, as compared to Limestone.
Acids:
Hydrochloric acid (HCL) is the preferred acid used in the acid test by scientists. Handling of this very dangerous acid should be left to the professionals. As a geocacher out in the field, you will be asked to use vinegar (CH3COOH) as a substitute. Vinegar is a diluted acetic acid solution of 5% to 10%. Effervescent reactions using Vinegar will not be as obvious as when using HCL so close inspection must be maintained.
Lime Production:
To produce lime, limestone must be burned with sufficient heat (750°F) to expel the carbon dioxide, altering the rock into lumps of lime and/or powdered lime. Temperatures from 1,000°F were generally used to make this reaction occur more quickly. Excessive temperature was avoided because it produced unreactive, "dead-burned" lime. Limestone was burned in either impermanent heaps, periodic kilns or continuous kilns. The finished product is also called quicklime.
Kiln Types:
Heap kilns were simply stacks of alternating layers of limestone blocks and wood fuel, stacked on the ground or in a pit. This was an expedient, although not efficient, means of lime production which was often used at the same time as land clearing operations. The quality of the log pile burn was impossible to control, resulting in lime of variable quality, mostly suitable for fertilizer.
For better quality and more efficiency, heap type kilns were replaced by periodic kilns. These types of kilns were constructed of stone and/or brick. These upright, bottle-shaped kilns have openings at both the base and at the top. Periodic kilns were one of the more primitive kiln types used during the pre-Civil War years, but were still far superior to heap kilns used for single-use or small-scale local lime production. For ease in loading the unburned stones, kilns were often dug into hillsides, earning them the nickname of "groundhog kilns". Quarried limestone could have been dumped directly into the mouth at the top of the kiln from a hand cart. Firing time for a periodic kiln burn would have been about 72 hours with an additional 12 hours for cooling time. The powdered lime could then be shoveled out of the opening at the bottom of the kiln and packed for shipping. The amount of hardwood fuel used for just a single burn would have been two to three times the volume of lime produced.
The perpetual, or continuous use kiln, came into use during the mid 1800s. These were of similar construction as to the periodic vertical type kilns. However, continuous use/perpetual kilns were loaded with alternating layers of wood fuel and stone, and after the initial firing, both stone and fuel would be continuously added into the top of the kiln. At the same time, cooked lime could be removed out the opening at the bottom. Because this type of kiln was in constant use, it required a steel lining to protect the brick/stone structure from crumbing.
Lime Usage:
During the 1800's, the most important use of lime (calcium oxide) was in the making of plaster and mortar for building construction. Mortar was used to hold stone and brick together in the building of walls and as chinking between the logs of log houses. Plaster was layered over wooden laths providing smooth-finished walls or ceilings in most homes and commercial buildings built during this time. Lime was also used in whitewash compound which was applied on the interior surfaces of log buildings. Chemical and manufacturing processes and agricultural applications also provided a market for lime in the nineteenth century.
The production of quicklime was eventually phased out around the turn of the century when artificial hydraulic cement came into production. Artificial cement was superior to the earlier product in that it set-up quicker and was stronger. A lower quality limestone could also be used in the burning process.
This is just over a 3 mile drive down a dirt road. When I drove this.....any auto could have completed it safely at slower speeds. It is basically a flat road. With the monsoons and flash flooding, as always, road conditions can change quickly.
Email your answers to the questions, to me, using the link in my profile only. If your answers are not received by me, your log will be deleted. Photos are accepted and appreciated as long as the answers are not pictured. You do not have to wait for confirmation from me before logging this cache as completed. Most of all……learn……and enjoy the view.
In 1879 George Puntenney arrived in Arizona. Soon thereafter he located an abundance of limestone and built the territory’s first limekiln. This was located on the south rim of Hell Canyon (Highway 89 crosses Hell Canyon about 40 miles north of Prescott). A total of 3 kilns were eventually built by George. Lime was an important commodity in the developing West. It was not only used in making mortar and plaster but also in the manufacturing of glass and castings, the refining of sugar and in the tanning of leather. Limewater, a solution of slaked lime, was used in many medicinal applications. Early actors aspired to stand in the brilliant light created by the oxidation of lime used in theater spotlights, hence the phrase "standing in the limelight". George operated the company up until 1929.
Forest Recreation Team Leader, Omero Torres, asked me to add this statement to the cache page. While anywhere within the Prescott National Forest please be respectful of natural resources and private land/property and to not alter or improve any natural or cultural sites.
