Dacite

Mylonite

Dacite and Mylonite

Dacite

Mylonite

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Definition

Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite

Mylonite is a metamorphic rock formed by ductile deformation during intense shearing encountered during folding and faulting, a process termed cataclastic or dynamic metamorphism

History

Origin

Romania and Moldova, Europe

New Zealand

Discoverer

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 Greek mulōn mill + -ite

Class

Igneous Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Aphanitic to Porphyritic

Foliated

Color

Bluish - Grey, Brown, Grey, Light to Dark Grey

Black to Grey

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Vesicular

Dull, Banded and Foilated

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Interior Decoration

Decorative Aggregates, Interior Decoration

Exterior Uses

As Building Stone, Paving Stone, Garden Decoration

As Building Stone, As Facing Stone, Paving Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

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

for Road Aggregate, Landscaping, Roadstone

Medical Industry

Antiquity Uses

Artifacts

Artifacts, Monuments

Other Uses

Commercial Uses

Commemorative Tablets, Creating Artwork

Creating Artwork, Gemstone, Jewelry

Types

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

Blastomylonites, Ultramylonites and Phyllonites

Features

Host Rock for Lead, Is one of the oldest rock

Surfaces are often shiny

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

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.

Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones.

Composition

Mineral Content

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

Porphyroblasts

Compound Content

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

Aluminium Oxide, Calcium Sulfate, Chromium(III) Oxide, Iron(III) Oxide, Magnesium Carbonate, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion

Chemical Erosion, Sea Erosion, Wind Erosion

Properties

Physical Properties

Hardness

2-2.253-4

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Fine Grained

Fracture

Conchoidal

Streak

White

Porosity

Less Porous

Highly Porous

Luster

Subvitreous to Dull

Shiny

Compressive Strength

70.00 N/mm²1.28 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Conchoidal

Toughness

Specific Gravity

2.86-2.872.97-3.05

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.77-2.771 g/cm³2.6-4.8 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K1.50 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Impact Resistant, Pressure Resistant

Reserves

Deposits in Eastern Continents

Asia

China, India, Indonesia, Saudi Arabia, South Korea

Africa

Eritrea, Ethiopia, Ghana, South Africa, Western Africa

Europe

France, Greece, Romania, Scotland, Spain

England, Finland, France, Germany, Great Britain, Greece, United Kingdom

Others

Deposits in Western Continents

North America

USA

South America

Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela

Deposits in Oceania Continent

Australia

New Zealand, South Australia, Western Australia

Central Australia, Western Australia

All about Dacite and Mylonite Properties

Know all about Dacite and Mylonite properties here. All properties of rocks are important as they define the type of rock and its application. Dacite belongs to Igneous Rocks while Mylonite belongs to Metamorphic Rocks.Texture of Dacite is Aphanitic to Porphyritic whereas that of Mylonite is Foliated. Dacite appears Vesicular and Mylonite appears Dull, Banded and Foilated. The luster of Dacite is subvitreous to dull while that of Mylonite is shiny. Dacite is available in bluish - grey, brown, grey, light to dark grey colors whereas Mylonite is available in black to grey colors. The commercial uses of Dacite are commemorative tablets, creating artwork and that of Mylonite are creating artwork, gemstone, jewelry.