Definition
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite
Amphibolite can be defined as a granular metamorphic rock which mainly consist of hornblende and plagioclase
Origin
Romania and Moldova, Europe
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Discoverer
Unknown
Alexandre Brongniart
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 Amphibole + -ite
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Aphanitic to Porphyritic
Banded, Foliated, Massive
Color
Bluish - Grey, Brown, Grey, Light to Dark Grey
Black, Brown, Green, Grey
Durability
Durable
Durable
Appearance
Vesicular
Foliated
Interior Uses
Decorative Aggregates, Entryways, Interior Decoration
Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Kitchens
Exterior Uses
As Building Stone, Paving Stone, Garden Decoration
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
As Dimension Stone, Building houses or walls, Cobblestones, Construction Aggregate, for Road Aggregate, Landscaping, Production of Glass and Ceramics, Roadstone
Antiquity Uses
Artifacts
Artifacts, Sculpture, Small Figurines
Commercial Uses
Commemorative Tablets, Creating Artwork
Cemetery Markers, Commemorative Tablets, Creating Artwork
Types
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite
Hornblendite
Features
Host Rock for Lead, Is one of the oldest rock
Clasts are smooth to touch, Matrix variable, Surfaces are often shiny
Archaeological Significance
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.
Amphibolite is a coarse-grained metamorphic rock which forms by metamorphism of mafic igneous rocks like basalt and gabbro or from the metamorphism of clay-rich sedimentary rocks like marl or graywacke.
Mineral Content
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Amphibole, Andalusite, Biotite, Calcite, Epidote, Garnet, Hornblade, Kyanite, Magnetite, Olivine, Plagioclase, Pyroxene, Staurolite, Wollastonite
Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism
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Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Wind Erosion
Grain Size
Medium to Fine Coarse Grained
Medium to Coarse Grained
Fracture
Conchoidal
Irregular to Conchoidal
Streak
White
White to Grey
Porosity
Less Porous
Less Porous
Luster
Subvitreous to Dull
Vitreous to Dull
Specific Gravity
2.86-2.87
2.5
Transparency
Translucent
Opaque
Density
2.77-2.771 g/cm3
2.85-3.07 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Africa
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Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Madagascar, Rwanda, Somalia, South Africa, Sudan, Tanzania, Uganda
Europe
France, Greece, Romania, Scotland, Spain
Germany, Greece, Iceland, Norway, Poland
Deposits in Western Continents
North America
USA
Canada, USA
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Brazil
Deposits in Oceania Continent
Australia
New Zealand, South Australia, Western Australia
South Australia, Western Australia