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Dacite and Hornfels


Hornfels and Dacite


Definition

Definition
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite   
Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat altered equivalent of the original rock   

History
  
  

Origin
Romania and Moldova, Europe   
New Zealand   

Discoverer
Unknown   
Unknown   

Etymology
From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described   
From German which means hornstone   

Class
Igneous Rocks   
Metamorphic Rocks   

Sub-Class
Durable Rock, Soft Rock   
Durable Rock, Soft Rock   

Family
  
  

Group
Volcanic   
Not Applicable   

Other Categories
Fine Grained Rock, Medium Grained Rock, Opaque Rock   
Fine Grained Rock, Opaque Rock   

Texture

Texture
Aphanitic to Porphyritic   
Granular, Platy   

Color
Bluish - Grey, Brown, Grey, Light to Dark Grey   
Brown, Dark Greenish - Grey, Green, Reddish Brown   

Maintenance
Less   
Less   

Durability
Durable   
Durable   

Water Resistant
No   
Yes   

Scratch Resistant
No   
No   

Stain Resistant
No   
No   

Wind Resistant
No   
No   

Acid Resistant
No   
No   

Appearance
Vesicular   
Dull   

Uses

Architecture
  
  

Interior Uses
Decorative Aggregates, Entryways, Interior Decoration   
Decorative Aggregates, Flooring, Homes, Interior Decoration   

Exterior Uses
As Building Stone, Paving Stone, Garden Decoration   
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone   

Other Architectural Uses
Curbing   
Curbing   

Industry
  
  

Construction Industry
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping   
for Road Aggregate, Roadstone   

Medical Industry
Not Yet Used   
Not Yet Used   

Antiquity Uses
Artifacts   
Artifacts, Monuments   

Other Uses
  
  

Commercial Uses
Commemorative Tablets, Creating Artwork   
Cemetery Markers, Commemorative Tablets, Creating Artwork   

Types

Types
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite   
Biotite hornfels   

Features
Host Rock for Lead, Is one of the oldest rock   
Smooth to touch   

Archaeological Significance
  
  

Monuments
Not Yet Used   
Used   

Famous Monuments
Not Applicable   
Data Not Available   

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
Absent   
Absent   

Formation

Formation
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.   
Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Hornfels is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.   

Composition
  
  

Mineral Content
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon   
Andalusite   

Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide   
Fe, Mg   

Transformation
  
  

Metamorphism
Yes   
No   

Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism   
Not Applicable   

Weathering
Yes   
Yes   

Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering   
Biological Weathering   

Erosion
Yes   
Yes   

Types of Erosion
Chemical Erosion   
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion   

Properties

Physical Properties
  
  

Hardness
2-2.25   
2-3   

Grain Size
Medium to Fine Coarse Grained   
Fine Grained   

Fracture
Conchoidal   
Conchoidal   

Streak
White   
Unknown   

Porosity
Less Porous   
Highly Porous   

Luster
Subvitreous to Dull   
Shiny   

Compressive Strength
Not Available   
5.80 N/mm2   
31

Cleavage
Perfect   
Perfect   

Toughness
Not Available   
Not Yet Found   

Specific Gravity
2.86-2.87   
3.4-3.9   

Transparency
Translucent   
Opaque   

Density
2.77-2.771 g/cm3   
0.25-0.30 g/cm3   

Thermal Properties
  
  

Specific Heat Capacity
0.92 kJ/Kg K   
10
0.84 kJ/Kg K   
15

Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant   
Heat Resistant, Impact Resistant, Pressure Resistant   

Reserves

Deposits in Eastern Continents
  
  

Asia
Not Yet Found   
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand   

Africa
Not Yet Found   
Cameroon, East Africa, Tanzania, Western Africa   

Europe
France, Greece, Romania, Scotland, Spain   
United Kingdom   

Others
Not Yet Found   
Not Yet Found   

Deposits in Western Continents
  
  

North America
USA   
Canada, USA   

South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela   
Bolivia, Brazil, Colombia, Ecuador   

Deposits in Oceania Continent
  
  

Australia
New Zealand, South Australia, Western Australia   
New South Wales, New Zealand, Queensland, Western Australia   

Summary >>
<< Reserves

All about Dacite and Hornfels Properties

Know all about Dacite and Hornfels properties here. All properties of rocks are important as they define the type of rock and its application. Dacite belongs to Igneous Rocks while Hornfels belongs to Metamorphic Rocks.Texture of Dacite is Aphanitic to Porphyritic whereas that of Hornfels is Granular, Platy. Dacite appears Vesicular and Hornfels appears Dull. The luster of Dacite is subvitreous to dull while that of Hornfels is shiny. Dacite is available in bluish - grey, brown, grey, light to dark grey colors whereas Hornfels is available in brown, dark greenish - grey, green, reddish brown colors. The commercial uses of Dacite are commemorative tablets, creating artwork and that of Hornfels are cemetery markers, commemorative tablets, creating artwork.

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