Definition
Basalt is a common extrusive igneous rock formed by the rapid cooling of basaltic lava exposed at or very near the surface of Earth
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite
History
Origin
Egypt
Romania and Moldova, Europe
Discoverer
Georgius Agricola
Unknown
Etymology
From Late Latin Basaltes (variant of basanites ), very hard stone, which was imported from Ancient Greek Basanites
From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Family
Group
Volcanic
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
Aphanitic to Porphyritic
Color
Black, Brown, Light to Dark Grey
Bluish - Grey, Brown, Grey, Light to Dark Grey
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Dull and Soft
Vesicular
Architecture
Interior Uses
Floor Tiles, Homes, Hotels, Kitchens
Decorative Aggregates, Entryways, Interior Decoration
Exterior Uses
As Building Stone, Paving Stone, Garden Decoration, Office Buildings
As Building Stone, Paving Stone, Garden Decoration
Other Architectural Uses
Curbing, Whetstones
Curbing
Industry
Construction Industry
Arrowheads, As Dimension Stone, Cobblestones, Cutting Tool, Rail Track Ballast, Roadstone
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments
Artifacts
Other Uses
Commercial Uses
An Oil and Gas Reservoir, Commemorative Tablets, Creating Artwork, Used in aquariums
Commemorative Tablets, Creating Artwork
Types
Alkaline Basalt, Boninite, High Alumina Basalt, Mid Ocean Ridge Basalt (MORB), Tholeiitic Basalt, Basaltic trachyandesite, Mugearite and Shoshonite
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite
Features
Has High structural resistance against erosion and climate, Very fine grained rock
Host Rock for Lead, Is one of the oldest rock
Archaeological Significance
Monuments
-
-
Famous Monuments
Easter Island in the Polynesian Triangle, Pacific Ocean, Gateway of India in Mumbai, India, Gol Gumbaz in Karnataka, India
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
Formation
Basalt forms when lava reaches the Earth's surface near an active volcano. The temperature of lava is between 1100 to 1250° C when it gets to the surface.
Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.
Composition
Mineral Content
Olivine, Plagioclase, Pyroxene
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
-
Chemical Erosion
Physical Properties
Hardness
62-2.25
1
7
👆🏻
Grain Size
Fine Grained
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Streak
White to Grey
White
Porosity
Less Porous
Less Porous
Luster
-
Subvitreous to Dull
Compressive Strength
37.40 N/mm270.00 N/mm2
0.15
450
👆🏻
Cleavage
-
Perfect
Toughness
2.3
-
Specific Gravity
2.8-32.86-2.87
0
8.4
👆🏻
Transparency
Opaque
Translucent
Density
2.9-3.1 g/cm32.77-2.771 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.84 kJ/Kg K0.92 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
India, Russia
-
Africa
South Africa
-
Europe
Iceland
France, Greece, Romania, Scotland, Spain
Others
-
-
Deposits in Western Continents
North America
Canada, USA
USA
South America
Brazil
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
-
New Zealand, South Australia, Western Australia