People then discovered how to skillfully break the obsidian to produce cutting tools in a variety of shapes. Obsidian was used to make knives, arrowheads, spear points, scrapers, and many other weapons and tools. Once these discoveries were made, obsidian quickly became the raw material of preference for producing almost any sharp object.
The easy-to-recognize rock became one of the first targets of organized "mining. Apache tears: "Apache Tears" is a name used for small obsidian nodules of about one inch or less that can be found in volcanic areas of the southwestern United States. Their name comes from a Native American legend. During a battle between Apaches and the U. Cavalry in , the outnumbered Apaches, facing defeat, rode their horses over a cliff rather than allow themselves to be killed by their enemy.
Upon hearing the story of the battle, the tears of their family members turned to stone when they hit the ground. Those stones are now found as the black obsidian nodules. People who do rock tumbling often polish Apache Tears. They are difficult to polish because the obsidian chips and bruises easily. Success occurs when they are cushioned during the tumbling with smaller pieces of rough or small ceramic media. The manufacture of obsidian tools by humans dates back to the Stone Age.
At some locations, tons of obsidian flakes reveal the presence of ancient "factories. Making arrowheads, spear points, knife blades, and scrapers from obsidian, chert , or flint might have been the world's first "manufacturing industry. Obsidian was so valued for these uses that ancient people mined, transported, and traded obsidian and obsidian objects over distances of up to a thousand miles.
Archaeologists have been able to document the geography of this trade by matching the characteristics of obsidian in outcrops with the characteristics of obsidian in cutting tools. A study done by the Idaho National Laboratory used composition studies by X-ray fluorescence to identify the source outcrops of obsidian artifacts and map their use across the western United States. Although using a rock as a cutting tool might sound like "stone age equipment," obsidian continues to play an important role in modern surgery.
Obsidian can be used to produce a cutting edge that is thinner and sharper than the best surgical steel. Today, thin blades of obsidian are placed in surgical scalpels used for some of the most precise surgery. In controlled studies, the performance of obsidian blades was equal to or superior to the performance of surgical steel. Obsidian jewelry: Mahogany obsidian and snowflake obsidian cabochons set in sterling silver pendants.
Obsidian for opal triplets: A thin piece of obsidian is often used as a "backing" material for opal doublets and triplets. The black obsidian adds stability to the opal and provides a dark background color that contrasts with the opal's fire. Obsidian is a popular gemstone. It is often cut into beads and cabochons or used to manufacture tumbled stones. Obsidian is sometimes faceted and polished into highly reflective beads. Some transparent specimens are faceted to produce interesting gems.
The use of obsidian in jewelry can be limited by its durability. It has a hardness of about 5. It also lacks toughness and is easily broken or chipped upon impact.
These durability concerns make obsidian an inappropriate stone for rings and bracelets. It is best suited for use in low-impact pieces such as earrings, brooches, and pendants. Obsidian is also used in making opal doublets and opal triplets. Thin slices or chips of opal are glued to a thin slice of obsidian to make a composite stone. The bubbles can be seen readily with a strong magnifying glass or a microscope. Obsidian is relatively unstable from a geologic perspective.
It is rare to find obsidian older than about 20 million years, which is very youthful in comparison to most continental rocks that form the Earth's crust. Over a long period of time, obsidian gradually changes from glass to rock in a process known as "devitrification.
The "snowflakes" in snowflake obsidian are quartz crystals that have formed through devitrification of the original obsidian. The crystals that develop through devitrification cause obsidian to lose its conchoidal fracture and glassy texture. Native Americans discovered almost all of the obsidian locations in North America. Each obsidian source area has a unique assemblage of trace elements, allowing identification of the original source locality for the obsidian used in prehistoric artifacts.
Trace element analyses have shown that native peoples traded this valuable commodity many hundreds of miles from the volcanic source areas along numerous trade routes. The fact that obsidian was transported great distances attests to the mystique of this unique material. My favorite place to collect obsidian is Glass Buttes in central Oregon. A trip to Glass Buttes is well worth the effort for the natural scenery, abundant and beautiful gem-quality obsidian, and exploration of a fascinating geological area.
These sagebrush- and juniper-covered hills are remote but accessible by automobile. Located in central Oregon south of Highway 20 and about 80 miles east of Bend, a visitor will be rewarded with many different varieties of obsidian through exploration of the area. Fist-sized pieces are abundant and can be collected with no digging.
For large pieces of high quality obsidian ranging up to several hundred pounds , considerable effort with a shovel and pry bar are necessary. Further information on Glass Buttes can be found in several rockhound guidebooks that include the central Oregon area. Examples of obsidian from Glass Buttes and stone tools made from those materials by the author are included with this article. Several varieties of obsidian from Glass Buttes, Oregon and tools made by the author from those materials.
From left to right across the top, the obsidian varieties are silver sheen, midnight lace, pumpkin and red mahogany. Skip to main content. Toggle menu Go to search page. Search Field. You are here Home » Volcanic Minerals. Source material and stone tools of red mahogany obsidian.
Pencil gives scale. Source material and stone tool of silver sheen obsidian. Source material and stone tools of pumpkin obsidian. Multi-colored streaks oriented along flow lines in midnight lace obsidian.
Pieces of fist size can be found on the surface in abundance here. It has a distinctive appearance of smooth glass. Obsidian is a frozen liquid that contains small amounts of mineral impurities. See the color Because pure obsidian is usually dark, on rare occasions it may also be almost white.
Consider the effect of impurities on the obsidian color For examples, iron and magnesium may make obsidian dark green. Hematite or limonite add a red or brown color to the obsidian. A lot of microscopic rock and mineral particles usually cause the jet black color most closely associated with obsidian.
It can cause the obsidian to have a gold or silver shine if the bubbles were spread almost flat. Obsidian has a strong conchoidal fracture and luster. It means that the top of the fracture is curving smoothly like a seashell. Obsidian appears to be black. Minute inclusions and tiny crystals in the glass create it hue.
Due to the near absence of mineral crystals in the glass, this smooth, curved form of fracture surface occurs. Conchoidal fracture surface intersections may be sharper than a knife. Obsidian, igneous rock that occurs as a natural glass produced by the rapid refreshment of viscous volcanic lava. Obsidian is extremely silica-rich around 65 to 80 percent , low in water, and has a rhyolite-like chemical composition. Obsidian has a luster of glass and is somewhat stronger than window glass.
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