Definition
Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat
  
Pumice is a volcanic rock that consists of highly vesicular rough textured volcanic glass, which may or may not contain crystals
  
History
  
  
Origin
France
  
Spain
  
Discoverer
Unknown
  
Unknown
  
Etymology
From French, Latin lignum wood + -ite1
  
From Old French pomis, from a Latin dialect variant of pumex
  
Class
Sedimentary Rocks
  
Igneous Rocks
  
Sub-Class
Durable Rock, Soft Rock
  
Durable Rock, Medium Hardness Rock
  
Family
  
  
Group
Not Applicable
  
Volcanic
  
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Amorphous, Glassy
  
Vesicular
  
Color
Black, Brown, Dark Brown, Grey, Light to Dark Grey
  
Beige, Colourless, Grey, Light Green, Light Grey, Pink, White, Yellow- grey
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
No
  
Yes
  
Scratch Resistant
No
  
Yes
  
Stain Resistant
No
  
Yes
  
Wind Resistant
No
  
No
  
Acid Resistant
No
  
Yes
  
Appearance
Veined or Pebbled
  
Vesicular
  
Architecture
  
  
Interior Uses
Not Yet Used
  
Decorative Aggregates, Flooring, Homes, Interior Decoration
  
Exterior Uses
Not Yet Used
  
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
  
Other Architectural Uses
Not Yet Used
  
Curbing, Powder
  
Industry
  
  
Construction Industry
for Road Aggregate, Steel Production
  
As Dimension Stone, Cement Manufacture, for Road Aggregate, In landscaping and horticulture, Making natural cement, Production of lightweight concrete blocks
  
Medical Industry
Not Yet Used
  
As an abrasive in skin exfoliating products, In Chemical and Pharmaceutical Industry, Medicines and Cosmetics
  
Antiquity Uses
Not Yet Used
  
Artifacts
  
Other Uses
  
  
Commercial Uses
Electricity Generation
  
As a traction material on snow-covered roads, As an abrasive in pencil erasers, Fine abrasive used for polishing, Manufacture of Soap, Solvents, Dyes, Plastics and Fibres, Used in aquariums
  
Types
Xyloid Lignite or Fossil Wood and Compact Lignite or Perfect Lignite
  
Scoria
  
Features
Generally rough to touch, Helps in production of Heat and Electricity, Used as fossil fuel
  
Host Rock for Lead
  
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
  
Pictographs
Used
  
Used
  
Petroglyphs
Used
  
Used
  
Figurines
Not Yet Used
  
Not Yet Used
  
Fossils
Present
  
Absent
  
Formation
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.
  
Pumice rock forms when the magma cools so quickly that atoms in the melt are not able to arrange themselves into a crystalline structure.
  
Composition
  
  
Mineral Content
Not Available
  
Aluminum Oxides, Calcite, Carbonate, Iron Oxides, Silica
  
Compound Content
Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur
  
Al, Aluminium Oxide, CaO, Carbon Dioxide, MgO, Silicon Dioxide
  
Transformation
  
  
Metamorphism
No
  
Yes
  
Types of Metamorphism
Not Applicable
  
Burial Metamorphism, Impact Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Water Erosion, Wind Erosion
  
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
1
  
6
  
Grain Size
Medium to Fine Coarse Grained
  
Fine Grained
  
Fracture
Conchoidal
  
Planar
  
Streak
Black
  
White, Greenish White or Grey
  
Porosity
Highly Porous
  
Highly Porous
  
Luster
Dull to Vitreous to Submetallic
  
Earthy
  
Compressive Strength
Not Available
  
51.20 N/mm
2
  
26
Cleavage
Non-Existent
  
Perfect
  
Toughness
Not Available
  
3
  
Specific Gravity
1.1-1.4
  
2.86
  
Transparency
Opaque
  
Opaque
  
Density
800-801 g/cm3
  
0.25-0.3 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
1.26 kJ/Kg K
  
5
0.87 kJ/Kg K
  
14
Resistance
Heat Resistant
  
Impact Resistant, Pressure Resistant
  
Deposits in Eastern Continents
  
  
Asia
Bangladesh, Burma, Cambodia, China, India, Indonesia, Kazakhstan, Malaysia, Mongolia, Pakistan, Turkey, Vietnam
  
Afghanistan, Indonesia, Japan, Russia
  
Africa
Botswana, Kenya, Morocco, Mozambique, South Africa, Tanzania
  
Ethiopia, Kenya, Tanzania
  
Europe
Belgium, Bulgaria, England, France, Germany, Greece, Hungary, Kosovo, Netherlands, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, The Czech Republic, Ukraine, United Kingdom
  
Greece, Hungary, Iceland, Italy, Turkey
  
Others
Not Yet Found
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
Canada, Mexico, USA
  
Bahamas, Barbados, Canada, Costa Rica, Cuba, Jamaica, Mexico, USA
  
South America
Brazil, Chile, Colombia, Venezuela
  
Argentina, Chile, Ecuador, Peru
  
Deposits in Oceania Continent
  
  
Australia
New South Wales, Queensland, Victoria
  
New Zealand, Western Australia