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
Anthracite is a type of sedimentary rock which is hard and is variety of coal that has high luster
Origin
Ethiopia
Pennsylvania, U.S.
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From Greek anthrakites, from anthrax, anthrak meaning coal
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Other Categories
Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Glassy
Amorphous, Glassy
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Brown, Dark Brown, Grey, Light to Dark Grey
Durability
Durable
Durable
Appearance
Shiny
Veined or Pebbled
Interior Uses
Decorative Aggregates, Interior Decoration
-
Exterior Uses
Garden Decoration
-
Other Architectural Uses
-
-
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Cement Manufacture, for Road Aggregate, Making natural cement, Steel Production
Medical Industry
Surgery
In Chemical and Pharmaceutical Industry, Manufacture of Aspirins
Antiquity Uses
Artifacts, Jewellery
-
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Alumina Refineries, Electricity Generation, Liquid Fuel, Manufacture of Soap, Solvents, Dyes, Plastics and Fibres, Paper Industry
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Semi-anthracite and Meta-anthracite
Features
Blocks negativity, Helps to protect against depression
Helps in production of Heat and Electricity, Used as fossil fuel
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.
Anthracite forms from the accumulation of plant debris in a swamp environment. When plant debris dies and falls into the swamp, the standing water of the swamp protects it from decay.
Mineral Content
-
Calcite, Clay, Clay Minerals
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Contact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
-
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
-
Grain Size
-
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Porosity
Very Less Porous
Less Porous
Specific Gravity
2.6-2.7
1.1-1.4
Transparency
Translucent
Opaque
Density
2.6 g/cm3
1.25-2.5 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Water Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
Bangladesh, Burma, Cambodia, China, India, Indonesia, Kazakhstan, Malaysia, Mongolia, Pakistan, Turkey, Vietnam
Africa
Kenya
Botswana, Kenya, Morocco, Mozambique, South Africa, Tanzania
Europe
Greece, Hungary, Iceland, Italy, Turkey
Belgium, Bulgaria, England, France, Germany, Greece, Hungary, Kosovo, Netherlands, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, The Czech Republic, Ukraine, United Kingdom
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, Mexico, USA
South America
Argentina, Chile, Ecuador, Peru
Brazil, Chile, Colombia, Venezuela
Deposits in Oceania Continent
Australia
New Zealand
New South Wales, Queensland, Victoria
All about Obsidian and Anthracite Properties
Know all about Obsidian and Anthracite properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Anthracite belongs to Metamorphic Rocks.Texture of Obsidian is Glassy whereas that of Anthracite is Amorphous, Glassy. Obsidian appears Shiny and Anthracite appears Veined or Pebbled. The luster of Obsidian is vitreous while that of Anthracite is shiny. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Anthracite is available in black, brown, dark brown, grey, light to dark grey colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Anthracite are alumina refineries, electricity generation, liquid fuel, manufacture of soap, solvents, dyes, plastics and fibres, paper industry.