Black obsidian – sappahire.com Black obsidian is a stone that gives you mental strength to get rid of negative attitudes. The surface of this stone, which has screaming properties, shines brightly. 1.How these are formed?
- Strength Of Obsidian
- Density Of Obsidian Rock
- How Strong Is Obsidian
- Obsidian Hardness
- Obsidian Grain Size
What is Obsidian? In this section, we will learn more about properties of Obsidian i.e. Physical and thermal properties. Physical properties of Obsidian include Color, Streak, Hardness, Structure, Cleavage, Fracture, Luster, Specific Gravity etc. The strength of Obsidian is 0.15 N/mm 2. Obsidian is a glassy black crystal with powerful grounding properties. To the stone's holder, that dark glossy surface is a source of strength and clarity. Mirror-like in bearing, the shiny pellet of. Obsidian Greatsword+5. Obsidian Greatsword is a Weapon in Dark Souls and Dark Souls Remastered. This greataxe, one of the rare dragon weapons, is formed by the tail of the one-eyed black dragon Kalameet, the last of the ancient dragons. The mystical power of its obsidian blade will be released when held with both hands.'
Home » Rocks » Igneous Rocks » Obsidian
What is Obsidian, How Does it Form, and What is it Used For?
Article by: Hobart M. King, PhD, RPG
Obsidian: The specimen shown above is about two inches (five centimeters) across. The curved semi-concentric ridges are breakage marks associated with obsidian's conchoidal fracture. The rock has very sharp edges.
What is Obsidian?
Obsidian is an igneous rock that forms when molten rock material cools so rapidly that atoms are unable to arrange themselves into a crystalline structure. It is an amorphous material known as a 'mineraloid.' The result is a volcanic glass with a smooth uniform texture that breaks with a conchoidal fracture (see photo).
Where Does Obsidian Form?
Obsidian is usually an extrusive rock - one that solidifies above Earth's surface. However, it can form in a variety of cooling environments:
- along the edges of a lava flow (extrusive)
- along the edges of a volcanic dome (extrusive)
- around the edges of a sill or a dike (intrusive)
- where lava contacts water (extrusive)
- where lava cools while airborne (extrusive)
Types of Obsidian: The specimens shown above are from Glass Butte rockhounding site in central Oregon. It shows the diversity of obsidian types that can be found in a small geographic area. Clockwise from upper left are: double flow obsidian, rainbow obsidian, black obsidian, pumpkin obsidian, mahogany obsidian, gold sheen obsidian, and the piece in the center is gold sheen. The nice photo above is from the Glass Butte Rockhounding Site page on the Deschutes National Forest website.
Mahogany obsidian: A tumble-polished specimen of 'mahogany obsidian.' Image copyright iStockphoto / Arpad Benedek.
What Color is Obsidian?
|
Black is the most common color of obsidian. However, it can also be brown, tan, or green. Rarely, obsidian can be blue, red, orange, or yellow. The colors are thought to be caused mainly by trace elements or inclusions.
Occasionally two colors of obsidian will be swirled together in a single specimen. The most common color combination is black and brown obsidian swirled together - that's called 'mahogany obsidian' (see photo).
As a 'glass,' obsidian is chemically unstable. With the passage of time, some obsidian begins to crystallize. This process does not happen at a uniform rate throughout the rock. Instead it begins at various locations within the rock. At these locations, the crystallization process forms radial clusters of white or gray cristobalite crystals within the obsidian. When cut and polished, these specimens are referred to as 'snowflake obsidian' (see photos).
Rarely, obsidian has an iridescent or metallic 'sheen' caused by light reflecting from minute inclusions of mineral crystals, rock debris, or gas. These colored specimens are known as 'rainbow obsidian,' 'golden obsidian,' or 'silver obsidian,' depending upon the color of the sheen or iridescence. These specimens are very desirable for the manufacture of jewelry.
Snowflake obsidian: A tumble-polished specimen of 'snowflake obsidian.' Image copyright iStockphoto / Martin Novak.
What is the Composition of Obsidian?
Most obsidians have a composition similar to rhyolite and granite. Granites and rhyolites can form from the same magma as obsidian and are often geographically associated with the obsidian.
Rarely, volcanic glasses are found with a composition similar to basalt and gabbro. These glassy rocks are named 'tachylyte.'
Are There Other Glassy Igneous Rocks?
Pumice, scoria, and tachylyte are other volcanic glasses formed by rapid cooling. Pumice and scoria differ from obsidian by having abundant vesicles - cavities in the rock produced when gas bubbles were trapped in a solidifying melt. Tachylyte differs in composition - it has a composition similar to basalt and gabbro.
Obsidian outcrop: Obsidian along the edge of a lava flow in central Oregon. Image copyright iStockphoto / Phil Augustavo.
Obsidian knife blade: A knife blade manufactured from mahogany obsidian. The craftsman who made this blade had a very high skill level and was able to produce a serrated edge. Image copyright iStockphoto / Al Braunworth.
Occurrence of Obsidian
Obsidian is found in many locations worldwide. It is confined to areas of geologically recent volcanic activity. Obsidian older than a few million years is rare because the glassy rock is rapidly destroyed or altered by weathering, heat, or other processes.
Significant deposits of obsidian are found in Argentina, Canada, Chile, Ecuador, Greece, Guatemala, Hungary, Iceland, Indonesia, Italy, Japan, Kenya, Mexico, New Zealand, Peru, Russia, United States, and many other locations.
In the United States it is not found east of the Mississippi River, as there is no geologically recent volcanic activity there. In the western US it is found at many locations in Arizona, California, Idaho, Nevada, New Mexico, Oregon, Washington, and Wyoming. Most obsidian used in the jewelry trade is produced in the United States.
Obsidian spear point: A spear point fashioned from opaque black obsidian. Image copyright iStockphoto / Charles Butzin.
Rock & Mineral Kits: Get a rock, mineral, or fossil kit to learn more about Earth materials. The best way to learn about rocks is to have specimens available for testing and examination.
Uses of Obsidian as a Cutting Tool
The conchoidal fracture of obsidian causes it to break into pieces with curved surfaces. This type of fracturing can produce rock fragments with very sharp edges. These sharp fragments may have prompted the first use of obsidian by people.
The first use of obsidian by people probably occurred when a sharp piece of obsidian was used as a cutting tool. 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.' It is probably a safe bet that all natural obsidian outcrops that are known today were discovered and utilized by ancient people.
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.S. Cavalry in 1870, 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.
Stone Age Manufacturing and Trade
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.' Some of these sites have enough waste debris to suggest that many people labored there for decades producing a variety of obsidian objects. 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.
Obsidian in Modern Surgery
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.
Uses of Obsidian in Jewelry
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 5.5 which makes it easy to scratch. 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 black obsidian provides an inexpensive and color-contrasting background that makes opal's colorful fire much more obvious. It also adds mass and stability to the opal that facilitates cutting it into a gem.
Other Uses of Obsidian
Freshly broken pieces of obsidian have a very high luster. Ancient people noticed that they could see a reflection in obsidian and used it as a mirror. Later, pieces of obsidian were ground flat and highly polished to improve their reflective abilities.
Obsidian's hardness of 5.5 makes it relatively easy to carve. Artists have used obsidian to make masks, small sculptures, and figurines for thousands of years.
More Rocks |
Rock, Mineral and Fossil Collections. |
Geodes |
Hardness Picks |
Fluorescent Minerals |
Flint, Chert, and Jasper |
Rock Salt |
Lapis Lazuli |
Tumbled Stones |
|
| ||
|
| ||
|
| ||
|
|
We know three main classes of rocks, sedimentary, igneous, and metamorphic. In Limestone article, we learned how sedimentation occurs, and the formation of sedimentary rocks takes place. Today, we are going to know Obsidian rock, which falls in the main class of igneous rocks.
We know igneous rocks have two basic types:
1. Intrusive Igneous Rocks
When molten lava/magma is cooling slowly below the surface of the earth and forms large crystals in the rocks they known as intrusive igneous rocks. For examples-
Diorite | Gabbro | Granite |
Pegmatite | Peridotite |
1 – Extrusive Igneous Rocks
When molten magma is cooling rapidly onto the surface of the earth and forms small crystals in the rocks they known as extrusive igneous rocks. For examples-
Obsidian | Andesite | Basalt |
Dacite | Pumice | Rhyolite |
Scoria | Tuff | Fire Opal |
Strength Of Obsidian
What Is Obsidian Rock?
If you strive to know the obsidian meaning, go ahead in this section. Obsidian is a class of igneous rocks, which forms when felsic lava extruded from a volcano onto the surface of the earth.
The cooling of lava takes place so rapidly that no chance remains for proper crystallization (Atomic Arrangements) and finds as an amorphous glass material. It has a smooth and uniform texture, which breaks with a conchoidal fracture.
Geological Classification of Obsidian Rocks:
Let’s see the classification of obsidian rocks at the perspectives of a geologist.
Class: Igneous RocksSub-Class: Medium Hardness Rocks Family-Group: Volcanic Category: Opaque Rocks Alternate Names: Lava, Glassy Lava, Xaga, Royal Agate, Glass Agate, Volcanic Glass, Glass Gem, Guardian Gem, and Black Beauty |
Formation of Obsidian Rocks in Nature
We have seen in the earlier section that obsidian is an extrusive rock type and formation used to takes place on the surface of the earth when magma or lava coming out due to volcanic phenomena and rapid cooling takes place. The obsidian formation can happen in a variety of cooling environment such as
- Along the edges of a flow of magma or lava
- Along the edges of a dome of the volcano
- Along the edges of a sill or dike, which takes place under the surface and it is the only intrusive type
- The point where magma comes into contact with water on the surface
- The point where magma cools due to airborne cooling effects
Natural Stone Pavers Collection | ||
Exotic Collection | Premia Collection | Porcelain Pavers |
Steps Stones | Window Sills | Pool Copings |
Properties of Obsidian
Obsidians have various physical & visual properties, such as Hardness, Grain Size, Fracture, Streak (Colors), Porosity, Luster, and Strength. These all property attributes determine the applications of obsidian rocks. Let’s see some significant properties of obsidians.
Specific Gravity & Density of Obsidian
The density of rock used to expresses as specific gravity, and it is measured in relevance to the density of water in gram per cubic centimeter of the mass. The density of obsidian is 2.55 g/cubic cm. It means it is heavier than water and dense medium as a mass.
Density Of Obsidian Rock
Streaks & Colors of ObsidianThe streak of obsidian is white, but various colors occur in nature. Frequently found colors of Obsidian rocks are: The highest occurrence of obsidians is in Black, but it also available in Brown, Green, or Tan. Rarely found colors of Obsidian rocks are: A very rare occurrence of obsidians is in Blue, Orange, Red, and Yellow. The occurrence of color is due to the presence of different trace elements in obsidian rocks. | The hardness of Obsidian (How Hard Is Obsidian Rocks)In physics and geology, the hardness of the physical objects or rocks is measured in Moh’s scale, which rates the objects in question on the scale from 1 to 10.
Based on Moh’s hardness scale, obsidians fall into a medium hard category of rocks because obsidian rocks have 5-5.5 Moh’s hardness scale. It also means obsidian is easy to scratch. |
Compressive Strength of ObsidianWhen a compressive pressure (In Newton unit) applied on the rocks a permanent deformation of rocks takes place at a point of pressure. It is termed as the compressive strength of rocks and obsidians fractured or permanently deformed at 0.15 N per square millimeter. It means obsidian is easy to break and chipped by some impacts. It also renders obsidian as the unfit stone for rings and bracelets like jewelry production. | Porosity of ObsidianIt is a less porous rock, so it has a medium hardness. |
Obsidian FractureObsidians breaks into the conchoidal fracture. Obsidian has no natural or defined planes of separation when a pressure exceeding its physical strength exerts on it. Therefore, smoothly curved fracture takes place on the surface of obsidian glass rock. The images at the side are depicting the phenomena beautifully and precisely. | Luster & Transparency of ObsidianIn Obsidian, only 1% of water exists. It means it is vitreous and due to the high presence of silica and other glass-forming minerals, it is translucent in transparency. |
What Type of Rock Is Obsidian?
Geologically, rocks used to divide into types. Based on the texture of the Obsidian rock types are decided. The main types of Obsidian rocks are as follows:
![Obsidian Obsidian](/uploads/1/1/2/1/112187645/342749227.jpg)
Mahogany Obsidian | When two colors, Black and Brown swirled together in a single obsidian rock, Mahogany Obsidian takes place. |
Obsidian is kind of glass and chemically unstable. Overtime crystallization process takes place in the mass of rock. If the formation of crystals happens in a radial cluster of white or gray crystals (cristobalite) at different and isolated locations, it referred to as Snowflake obsidian. | Snowflake Obsidian |
Rainbow Obsidian | Seldom obsidians have an iridescent or metallic “Sheen” thanks to the reflection of light rays. It used to takes place due to minute inclusions of mineral crystals, gas trapped in obsidian, and some debris. It results in a prismatic effect found due to the glass matter of obsidians, and white light rays are fragmenting in the rainbow color spectrum. |
If metallic sheen reflecting light rays in golden color, the gold sheen obsidians occur. In black obsidian, golden inclusions take place it shines as yellow and honey metals in the mass of obsidian. | Gold Sheen Obsidian |
Silver Sheen Obsidian | Similarly, if metallic sheen found in silver color, the silver sheen obsidians take place. |
When tiny bubbles of gas trapped in the rock and resulting in a reflection of purple color, a purple sheen obsidian happens. | Purple Sheen Obsidian |
Double Flow Obsidian | Sometimes the two different colors exist in the same specimen of the obsidian rock. Moreover, the occurrence of different colors takes place in a pattern of flows, and it is flowing in a different direction, we termed it a double flow obsidian. |
Black is the most common color found in obsidians. Therefore, the highest occurrence of obsidians found in the black glass. It projects a shiny black hue and popular as a black gemstone in the jewelry industry. | Black Obsidian |
Pumpkin Obsidian | When obsidian is reflecting mainly pumpkin color in pale brown shades, it called as pumpkin obsidian. It resembles Mahogany obsidians in looks and brown to black and beige bands of colors found in the mass of obsidians. |
Green-colored obsidians occur seldom and when polished they resemble emerald and used for jewelry purposes. It found in mossy to pickle green color shades. | Green Obsidian |
The occurrence of Obsidian Rocks in Different Geographic Regions of the Earth
Obsidian is falling into a volcanic-group of rocks. Therefore, the occurrence of Obsidian confined to geological areas where volcanic activity happened in the recent past. Obsidian rocks are not expected in volcanic areas of distance past like before billions of years because the glassy rocks are destroying rapidly due to weathering effects and various geological processes.
Significant deposits of obsidian rocks exist in the following continents of the world.
How Strong Is Obsidian
Asia: | Afghanistan, Indonesia, Japan, Armenia, Azerbaijan, and Russia. |
Africa: | Kenya. |
Europe: | Greece, Hungary, Iceland, Italy, Scotland, and Turkey. |
North America: | Canada, Mexico, and the USA. |
Central America: | El Salvador, Guatemala, and Papua New Guinea. |
>South America: | Argentina, Chile, Ecuador, and Peru. |
Australia: | New Zealand. |
The highest production of jewelry grade obsidians takes place in the United States. However, in the USA, obsidian rocks are not found in eastern regions of the Mississippi River because that area lacks volcanic activities in the recent past at all. The remaining areas of the States of America where obsidian rocks available are:
Arizona | California | Idaho | Nevada |
New Mexico | Oregon | Washington | Wyoming |
Colorado | Texas | Utah |
Obsidian Hardness
Obsidian rocks also available in Virginia, Pennsylvania, and North Carolina.
Obsidian Grain Size
Obsidian Uses
Now, I am going to acknowledge your use of obsidian. Do you know a conchoidal fracture of a rock resulting in pieces of rocks in curved surfaces?
Obsidian rocks can produce fragments with sharp edges, and sharp fragments of obsidian rocks first used as cutting tools in ancient eras of the civilization of humankind.
Today, a variety of uses found in different industries, such as:
Obsidians as Weapons & Tools:The human civilization has used obsidian rocks to make knives, spear points, arrowheads, scrapers, and various weapons. Knives and blades were fine for kitchen applications. Scrappers were used in land digging, agriculture, and gardening applications. Arrowheads and spear points were provided the sharpest tools for warriors in the creation of various weapons. |
Obsidians in Construction Industry:Obsidian rocks use in interior and exterior decoration. Decorative aggregates, gravels, and pebbles from obsidian rocks are a favorite material for creating architectural beauty and artwork on walls, ceilings, and floors of the buildings. Artworks in gardens, patios, swimming pools, fire features, and water features look amazing when obsidian rocks applied along with other Gemstones. It also used as mirror elements in the decoration of the interior, exterior, and construction of artifacts for various applications in life. |
Obsidians in Medical Surgery:Obsidian rocks are continuously used in the modern era to create cutting-edge surgical tools. Studies have revealed the fact that thin blades for scalpel of obsidians are superior in sharpness and performance than or equivalent to blades created from the latest surgical steel. Do you know household razor blades are 300-600 Angstroms while obsidian can produce blades of 30 Angstroms? It means obsidian can produce the sharpest materials that only Nanotechnologies can produce. If you look at the sharpest edge of the steel blade in the microscope, you will notice almost saw-like teeth on the edge. Whereas, the obsidian blade has no bite because it has an evenly smooth edge at the microscopic level. Therefore, wounds cut by obsidian blades are healing significantly faster than wounds by steel blades. |
Obsidians in Antiquity and Jewelry Industry:Obsidian rocks often cut into beads and cabochons. Mahogany and Snowflakes obsidian types of rocks are providing gemstones for earrings, brooches, and pendants. In the creation of Opal Doublets and Triplets, a thin slice of obsidian is glued as a backing material in the construction of composite gemstones. The black obsidian is an ideal material in making Opals to offer color-contrasting background. However, medium-strength of obsidian with 5.5 hardness creates durability concerns and the jewelry industry avoids its use as they apply diamonds and other gemstones. |
Obsidian Rocks for Sales
If you are curious about obsidian for sale, I would like to describe obsidian rocks for sale in a nutshell here.
Obsidians are delicate rocks for many jewelry applications where the chances of various impacts are high. So, the jewelry industry avoids the high usage of these natural rocks/gems/glasses. It mainly used in delicate jewelry, and the following varieties are popular for commercial usages of obsidians.
The richest market of obsidian for sales is aiming for heal purposes. It is believed that obsidian stones have natural healing capabilities. Therefore, along with described various obsidian types earlier, the following varieties of obsidian products are in demand in the healing gemstone market.
Apache Tears | Spiderweb | Cat Eye |
Flame/Fire | Peanut | Midnight Lace |
eBay and Etsy are popular marketplaces to obtain raw obsidians. Various eCommerce jewelry sites are selling ready to use jewelry made from different kinds of obsidian rocks and for a variety of jewelry products. The online marketplaces including Alibaba and others are selling sorted and unsorted rough obsidian natural stones are weighing from 1/4lb to 1-2lbs.
Wrapping It Up
In the series of identifying various rocks and natural stones at World of Stones, USA, we have explored different aspects of obsidian rocks such as meaning, uses, facts, properties, and colors of obsidians.
World of Stones, USA is an excellent place to buy a variety of natural rocks mainly used for exterior applications in the building construction industry. If you are interested to know about rocks and stones, keep reading blogs at World of Stones.