Dacite

Tephrite

Dacite and Tephrite

Dacite

Tephrite

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Definition

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

Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock

History

Origin

Romania and Moldova, Europe

Germany

Discoverer

Unknown

Van Tooren

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 tephra, ashes from Indo-European base, to burn

Class

Igneous Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Aphanitic to Porphyritic

Color

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

Black, Brown, Green, Grey, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Vesicular

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

Other Architectural Uses

Curbing

Industry

Construction Industry

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

Landscaping

Medical Industry

Antiquity Uses

Artifacts

Artifacts, Sculpture

Other Uses

Commercial Uses

Commemorative Tablets, Creating Artwork

Production of Lime, Soil Conditioner

Types

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

Igneous 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.

Tephrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.

Composition

Mineral Content

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

Alkali feldspar, Nepheline, Plagioclase, Pyroxene

Compound Content

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

CaO, Carbon Dioxide, MgO, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism

Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion

Properties

Physical Properties

Hardness

2-2.256.5

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Fracture

Conchoidal

Uneven

Streak

White

Bluish Black

Porosity

Less Porous

Very Less Porous

Luster

Subvitreous to Dull

Compressive Strength

70.00 N/mm²90.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Crenulation and Pervasive

Toughness

2.4

Specific Gravity

2.86-2.872.86

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.77-2.771 g/cm³2.8-2.9 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, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

Africa

Namibia, Uganda

Europe

France, Greece, Romania, Scotland, Spain

Germany, Hungary, Italy, Portugal, Spain

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

New Zealand, Western Australia

All about Dacite and Tephrite Properties

Know all about Dacite and Tephrite properties here. All properties of rocks are important as they define the type of rock and its application. Dacite and Tephrite belong to Igneous Rocks.Texture of Dacite is Aphanitic to Porphyritic whereas that of Tephrite is Aphanitic to Porphyritic. Dacite appears Vesicular and Tephrite appears Vesicular. The luster of Dacite and Tephrite is subvitreous to dull. Dacite is available in bluish - grey, brown, grey, light to dark grey colors whereas Tephrite is available in black, brown, green, grey, white colors. The commercial uses of Dacite are commemorative tablets, creating artwork and that of Tephrite are production of lime, soil conditioner.