Dacite

Pseudotachylite

Dacite and Pseudotachylite

Dacite

Pseudotachylite

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Definition

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

Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.

History

Origin

Romania and Moldova, Europe

USA

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 pseudo- +‎ tachylite, a glassy rock generated by frictional heat within faults.

Class

Igneous Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Aphanitic to Porphyritic

Quench

Color

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

Black, Brown, Green, Grey, Pink, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Vesicular

Dull and Soft

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

As Building Stone, Paving Stone, Garden Decoration

As Building Stone, As Facing Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

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

As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement

Medical Industry

Antiquity Uses

Artifacts

Artifacts, Monuments

Other Uses

Commercial Uses

Commemorative Tablets, Creating Artwork

Creating Artwork, Gemstone

Types

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

Cataclastic rock

Features

Host Rock for Lead, Is one of the oldest rock

Host Rock for Lead

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.

Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Pseudotachylite 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

Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides

Compound Content

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

Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion

Properties

Physical Properties

Hardness

2-2.257

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Very fine-grained

Fracture

Conchoidal

Uneven

Streak

White

Light to dark brown

Porosity

Less Porous

Luster

Subvitreous to Dull

Vitreous

Compressive Strength

70.00 N/mm²60.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

Specific Gravity

2.86-2.872.46-2.86

0 8.4

👆🏻

Transparency

Translucent

Transparent to Translucent

Density

2.77-2.771 g/cm³2.7-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

South Korea

Africa

Western Africa

Europe

France, Greece, Romania, Scotland, Spain

Great Britain, Switzerland

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 Pseudotachylite Properties

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