Why obsidian is not a mineral

The various colors of obsidian are a result of several factors. There are very few clear obsidian types, or microscopic mineral crystals. Obsidian red or brown usually results in small crystals or hematite or limonite iron oxide inclusions.

The jet-black types of obsidian are probable to generate abundant microscopic crystals of minerals such as magnet, hornblende, pyroxene, plagioclase, and biotites in combination with smaller pieces of rocken. The distinctive blue, green , violet or bronze colours of the rainbow obsidian may be obtained from a microscope of multiple feldspar kinds. Obsidian can be discovered in places with rhyolitical temperatures. The southern countries of Virginia, as well as Pennsylvania and North Carolina are also subject to obsidian.

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Share on Facebook. Solid: Liquids and gases are not considered minerals , in large part because their structure is constantly changing, which means they do not have a characteristic crystal structure. A true mineral must be solid. This orderly packing of atoms is seen and shaped as what many know today as crystals. Some naturally occurring solids, such as volcanic glass obsidian lack a repetitive atomic structure and are not considered minerals.

Natural glass obsidian is a volcanic rock, but it is not a ' mineral ' because glass is not crystalline: it is a supercooled liquid: no crystals had time to form. Man made glass is not a mineral because it is man- made not naturally occurring and also - it is not crystalline.

Why is obsidian not a mineral? Does Obsidian break easily? Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. Obsidian is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth. Obsidian is hard, brittle, and amorphous; it therefore fractures with sharp edges. What mineral is obsidian made of? Red or brown obsidian generally results from tiny crystals or inclusions of hematite or limonite iron oxide.

Abundant, microscopic crystals of minerals like magnetite, hornblende, pyroxene, plagioclase and biotite, combined with tiny fragments of rock, likely produce the jet-black varieties of obsidian. How much does Obsidian sell for?

How is obsidian collected? Because obsidian is easy to break like glass , collecting samples from an outcrop is relatively simple. A good rock hammer will easily break large chunks of volcanic glass into small, usable pieces.

However, make sure to bring a good collection bag because obsidian tends to be quite heavy. Is black obsidian magnetic? A slight increase in the amount of either could be enough to draw a magnet, although as Donald stated, those neodimium magnets are strong little animals..

Red or brown obsidian generally results from tiny crystals or inclusions of hematite or limonite iron oxide. Abundant, microscopic crystals of minerals like magnetite, hornblende, pyroxene, plagioclase and biotite, combined with tiny fragments of rock, likely produce the jet-black varieties of obsidian. Microscopic crystals of various types of feldspars may yield the unique blue, green, purple or bronze colors associated with rainbow obsidian. The reflectance of rainbow obsidian is likely attributed to a preferred orientation of microscopic crystals of feldspar or mica oriented along flow layers.

A certain amount of water always is present in obsidian. Very small inclusions of water vapor in the form of bubbles often are trapped in the glass. Tiny gas bubbles that have been stretched nearly flat along the flow layers in obsidian generally cause the reflectance of gold sheen and silver sheen obsidian.

Some of these bubbles are visible to the naked eye. 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.