Definition
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth
Banded iron formation are distinctive units of sedimentary rock that are almost always of Precambrian age
Origin
Ethiopia
Western Australia, Minnesota
Discoverer
Obsius
Johann Gottlob Lehmann
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From its formation process
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Other Categories
Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Glassy
Banded, Trellis
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Red, Reddish Brown
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Shiny
Layered, Banded, Veined and Shiny
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
Garden Decoration
Paving Stone, Office Buildings
Other Architectural Uses
-
Curbing, Whetstones
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
As Dimension Stone, Used for flooring, stair treads, borders and window sills.
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
As a touchstone, Cemetery Markers, Creating Artwork
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Algoma-type , Lake Superior-type, Superior-type and Taconite
Features
Blocks negativity, Helps to protect against depression
Is one of the oldest rock
Archaeological Significance
Formation
When the lava is released from volcano, it undergoes a very rapid cooling which freezes the mechanisms of crystallization. The result is a volcanic glass with a uniform smooth texture.
The banded iron layers are formed in sea water when oxygen is released by photosynthetic cyano-bacteria. The oxygen then combines with dissolved iron in ocean to form insoluble iron oxides, which precipitated out, forming a thin layer of banded iron formation on ocean floor.
Mineral Content
-
Hematite, Magnetite, Quartz
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Fe, Iron(III) Oxide, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
-
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Coastal Erosion, Wind Erosion
Grain Size
-
Large and Coarse Grained
Fracture
Conchoidal
Uneven, Splintery or Conchoidal
Porosity
Very Less Porous
Highly Porous
Specific Gravity
2.6-2.7
5.0-5.3
Transparency
Translucent
Translucent to Opaque
Density
2.6 g/cm3
-9999 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
China, India, Iran, Iraq, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Kenya
Kenya, Morocco, South Africa, Tanzania
Europe
Greece, Hungary, Iceland, Italy, Turkey
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
-
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, Mexico, USA
South America
Argentina, Chile, Ecuador, Peru
Bolivia, Brazil
Deposits in Oceania Continent
Australia
New Zealand
New South Wales, Queensland, South Australia, Western Australia
Obsidian vs Banded iron formation Characteristics
Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Obsidian vs Banded iron formation characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Obsidian and Properties of Banded iron formation. Learn more about Obsidian vs Banded iron formation in the next section. The interior uses of Obsidian include Decorative aggregates and Interior decoration whereas the interior uses of Banded iron formation include Decorative aggregates and Homes. Due to some exceptional properties of Obsidian and Banded iron formation, they have various applications in construction industry. The uses of Obsidian in construction industry include Arrowheads, Cutting tool, Knives, Scrapers, Spear points and that of Banded iron formation include As dimension stone, Used for flooring, stair treads, borders and window sills..
More about Obsidian and Banded iron formation
Here you can know more about Obsidian and Banded iron formation. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Obsidian and Banded iron formation consists of mineral content and compound content. The mineral content of Obsidian includes and mineral content of Banded iron formation includes Hematite, Magnetite, Quartz. You can also check out the list of all Igneous Rocks. When we have to compare Obsidian vs Banded iron formation, the texture, color and appearance plays an important role in determining the type of rock. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas, Banded iron formation is available in red, reddish brown colors. Appearance of Obsidian is Shiny and that of Banded iron formation is Layered, Banded, Veined and Shiny. Properties of rock is another aspect for Obsidian vs Banded iron formation. The hardness of Obsidian is 5-5.5 and that of Banded iron formation is 5.5-6. The types of Obsidian are Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian whereas types of Banded iron formation are Algoma-type , Lake Superior-type, Superior-type and Taconite. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Obsidian and Banded iron formation is white. The specific heat capacity of Obsidian is 0.92 kJ/Kg K and that of Banded iron formation is 3.20 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Obsidian is heat resistant, impact resistant whereas Banded iron formation is heat resistant, impact resistant, pressure resistant, wear resistant.