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Logging Requirements: To log this earthcache, send an email or message to the cache owner with answers to the following questions. Do NOT include in your log either the answers (even if encrypted) or photos of the boulder.
Questions from observations at posted coordinates:
(1) Is this hematite black or red-brown? Overall shiny or earthy?
(2) Estimate the length of the boulder
Questions from text:
(3) What color do you think the streak of this specimen will be?
(4) What two characteristics make hematite such a long-lasting pigment?
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The posted coordinates will bring you to a large boulder blocking an old trail. The scaly mineral deposits that you see running somewhat horizontally (parallel to the length of the boulder) are hematite.
Hematite is one of the most common minerals that make up the earth’s crust. It occurs in a range of textural forms from metallic/shiny to dull/earthy, and its color can range from black to gray, or from red to brown depending on which variety is present.
Specular Hematite (shiny black) Earthy Hematite (dull reddish-brown)
Having a chemical composition of Fe2O3 (a simple combination of two very abundant elements, iron and oxygen), hematite can be deposited from fluids as a primary mineral or can form secondarily as the product of chemical weathering of clay minerals. The large hematite-rich boulder you see here is the result of chemical weathering of feldspar, with several scaly patches of hematite visible lengthwise along the boulder.
Despite such a variety of origins and appearances, hematite can be easily identified by its “streak.” The term “streak” refers to the color of the finely powdered mineral. All varieties of hematite, from black to red, shiny to earthy, exhibit a distinctive reddish-brown streak that serves to distinguish it from most common minerals. Even the name Hematite is derived from the Greek word ‘haimatitis’, which means “blood-red,” after the color of the mineral in its powdered form.
Even black hematite produces a reddish-brown streak.
Thousands of years ago, primitive people discovered that a useful paint could be made from crushed hematite mixed with a liquid. Many ancient cave paintings or pictographs were created with hematite pigments. Because hematite is an opaque (not see-through) and permanent colorant, the artwork has been preserved until today.
Color varieties of Hematite pigment
Hematite was one of the most important pigments when the use of oil-based paints increased during the Renaissance period, and hematite continues to be one of the most important tinting minerals today. It has been mined at many locations around the world and has been traded extensively as a red pigment.
In addition to artists’ paint, hematite is used extensively in cosmetics and industrial paints and glazes due to its worldwide abundance and therefore low expense. Whether in lipstick or on red barns and fire trucks, most red pigments in our world today are composed of hematite.
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https://www.esci.umn.edu/courses/1001/minerals/hematite.shtml
http://geology.com/minerals/hematite.shtml
https://www.esci.umn.edu/courses/1001/minerals/hematite.shtml
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USFS rules state that geocaching is not permitted within Bent Creek Experimental Forest. Under a special use permit geocaches are permitted at The North Carolina Arboretum when placed and maintained by Arboretum staff only. Please refrain from adding additional caches.
The North Carolina Arboretum was established in 1986, and features a 434-acre public garden with over 10 miles of hiking and biking trails. For more information on fees and policies, visit our website at www.ncarboretum.org.