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
Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From French, Latin lignum wood + -ite1
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Group
Volcanic
Not Applicable
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
Not Yet Used
Exterior Uses
Garden Decoration
Not Yet Used
Other Architectural Uses
Not Yet Used
Not Yet Used
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
for Road Aggregate, Steel Production
Medical Industry
Surgery
Not Yet Used
Antiquity Uses
Artifacts, Jewellery
Not Yet Used
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Electricity Generation
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Xyloid Lignite or Fossil Wood and Compact Lignite or Perfect Lignite
Features
Blocks negativity, Helps to protect against depression
Generally rough to touch, Helps in production of Heat and Electricity, Used as fossil fuel
Archaeological Significance
Monuments
Not Yet Used
Not Yet Used
Famous Monuments
Not Applicable
Not Applicable
Sculpture
Not Yet Used
Not Yet Used
Famous Sculptures
Not Applicable
Not Applicable
Figurines
Not Yet Used
Not Yet Used
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.
Coal formation takes place due to accumulation of plant debris in a swamp environment. The Coal formation process continues, as peat turns into lignite brown or black coal at increasing heat and pressure.
Mineral Content
Not Available
Not Available
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
Not Applicable
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Water Erosion, Wind Erosion
Grain Size
Not Applicable
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Porosity
Very Less Porous
Highly Porous
Luster
Vitreous
Dull to Vitreous to Submetallic
Compressive Strength
Not Available
Cleavage
Non-Existent
Non-Existent
Toughness
Not Available
Not Available
Specific Gravity
2.6-2.7
1.1-1.4
Transparency
Translucent
Opaque
Density
2.6 g/cm3
800-801 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat 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
Others
Not Yet Found
Not Yet Found
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
Obsidian vs Lignite 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 Lignite characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Obsidian and Properties of Lignite. Learn more about Obsidian vs Lignite in the next section. The interior uses of Obsidian include Decorative aggregates and Interior decoration whereas the interior uses of Lignite include Not yet used. Due to some exceptional properties of Obsidian and Lignite, 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 Lignite include For road aggregate, Steel production.
More about Obsidian and Lignite
Here you can know more about Obsidian and Lignite. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Obsidian and Lignite consists of mineral content and compound content. The mineral content of Obsidian is not available and mineral content of Lignite is not available. You can also check out the list of all Igneous Rocks. When we have to compare Obsidian vs Lignite, 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, Lignite is available in black, brown, dark brown, grey, light to dark grey colors. Appearance of Obsidian is Shiny and that of Lignite is Veined or Pebbled. Properties of rock is another aspect for Obsidian vs Lignite. The hardness of Obsidian is 5-5.5 and that of Lignite is 1. The types of Obsidian are Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian whereas types of Lignite are Xyloid Lignite or Fossil Wood and Compact Lignite or Perfect Lignite. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Obsidian is white while that of Lignite is black. The specific heat capacity of Obsidian is 0.92 kJ/Kg K and that of Lignite is 1.26 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 Lignite is heat resistant.