Definition
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers called coal beds
Ignimbrite is a volcanic rock consisting mainly of pumice fragments, formed by the consolidation of material deposited by pyroclastic flows
Discoverer
John Peter Salley
Patrick Marshall
Etymology
From the Old English term col, which has meant mineral of fossilized carbon since the 13th century
From Latin ignis fire + imber, imbr- shower of rain, storm cloud + -ite
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Amorphous, Glassy
Aphanitic
Color
Black, Brown, Dark Brown, Grey, Light to Dark Grey
Beige, Black, Brown, Grey, Pink, White
Durability
Durable
Durable
Appearance
Veined or Pebbled
Dull, Vesicular and Foilated
Interior Uses
-
Decorative Aggregates, Floor Tiles, Homes, Interior Decoration
Exterior Uses
-
As Building Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
-
Curbing
Construction Industry
Cement Manufacture, for Road Aggregate, Making natural cement, Steel Production
Building houses or walls, Construction Aggregate
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Alumina Refineries, Electricity Generation, Liquid Fuel, Manufacture of Soap, Solvents, Dyes, Plastics and Fibres, Paper Industry
Cemetery Markers, Commemorative Tablets, Creating Artwork
Types
Peat, Lignite, Sub-Bituminous Coal, Bituminous Coal, Anthracite, Graphite
Pyroclastic rock
Features
Helps in production of Heat and Electricity, Used as fossil fuel
Always found as volcanic pipes over deep continental crust
Archaeological Significance
Formation
Coal forms from the accumulation of plant debris in a swamp environment which is buried by sediments such as mud or sand and then compacted to form coal.
Ignimbrites are formed from very poorly sorted mixture of volcanic ash or tuff and pumice lapilli, commonly with scattered lithic fragments.
Mineral Content
Analcime, Apatite, Barite, Calcite, Chalcopyrite, Chlorite, Chromite, Clausthalite, Clay Minerals, Crandallite Group, Dolomite, Feldspar, Galena, Gypsum, Marcasite, Muscovite or Illite, Pyrite, Quartz, Siderite, Sphalerite, Zircon
Apatite, Biotite, Calcite, Chlorite, Feldspar, Hematite, Hornblade, Ilmenite, Magnetite, Olivine, Pyroxene, Quartz
Compound Content
Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur
Ca, NaCl
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Burial Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
-
Biological Weathering, Chemical Weathering
Types of Erosion
-
Chemical Erosion, Coastal Erosion
Grain Size
Medium to Fine Coarse Grained
Fine Grained
Fracture
Conchoidal
Uneven
Porosity
Less Porous
Highly Porous
Luster
Dull to Vitreous to Submetallic
Vitreous to Dull
Specific Gravity
1.1-1.4
2.73
Transparency
Opaque
Opaque
Density
1100-1400 g/cm3
1-1.8 g/cm3
Resistance
Heat Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Bangladesh, Burma, Cambodia, China, India, Indonesia, Kazakhstan, Malaysia, Mongolia, Pakistan, Turkey, Vietnam
Afghanistan, Armenia, Azerbaijan, Burma, Cambodia, China, India, Indonesia, Iran, Japan, Malaysia, Mongolia, Nepal, North Korea, Pakistan, Saudi Arabia, Syria, Taiwan, Thailand, Turkey, Vietnam, Yemen
Africa
Botswana, Kenya, Morocco, Mozambique, South Africa, Tanzania
Cameroon, Cape Verde, Chad, Djibouti, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Nigeria, Rwanda, South Africa, Sudan, Tanzania, Uganda
Europe
Belgium, Bulgaria, England, France, Germany, Greece, Hungary, Kosovo, Netherlands, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, The Czech Republic, Ukraine, United Kingdom
France, Georgia, Germany, Greece, Iceland, Italy, Netherlands, Poland, Portugal, Spain, United Kingdom
Others
-
Antarctica, Hawaii Islands
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, Costa Rica, Panama, USA
South America
Brazil, Chile, Colombia, Venezuela
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador
Deposits in Oceania Continent
Australia
New South Wales, Queensland, Victoria
Central Australia, Western Australia