Tephrite

Variolite

Tephrite and Variolite

Tephrite

Variolite

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Definition

Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock

Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance

History

Origin

Germany

France

Discoverer

Van Tooren

Unknown

Etymology

From Greek tephra, ashes from Indo-European base, to burn

From Latin varius, speckled, variegated

Class

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

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

Opaque Rock

Texture

Aphanitic to Porphyritic

Glassy, Massive, Porphyritic, Scoriaceous, Vesicular

Color

Black, Brown, Green, Grey, White

Black, Brown, Light to Dark Grey

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, Flooring, Homes, Interior Decoration

Floor Tiles, Flooring, Homes, Hotels, Kitchens

Exterior Uses

As Building Stone, As Facing Stone, Garden Decoration, Office Buildings

Garden Decoration, Office Buildings

Other Architectural Uses

Curbing

Industry

Construction Industry

Landscaping

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Medical Industry

Antiquity Uses

Artifacts, Sculpture

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Production of Lime, Soil Conditioner

Cemetery Markers, Creating Artwork

Types

Igneous rock

Metamorphic rock

Features

Host Rock for Lead

Has High structural resistance against erosion and climate, Very fine grained rock

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

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.

Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.

Composition

Mineral Content

Alkali feldspar, Nepheline, Plagioclase, Pyroxene

Olivine, Plagioclase, Pyroxene

Compound Content

CaO, Carbon Dioxide, MgO, Silicon Dioxide

Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

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

Properties

Physical Properties

Hardness

6.56

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Fracture

Uneven

Conchoidal

Streak

Bluish Black

White to Grey

Porosity

Very Less Porous

Less Porous

Luster

Subvitreous to Dull

Compressive Strength

90.00 N/mm²37.50 N/mm²

0.15 450

👆🏻

Cleavage

Crenulation and Pervasive

Toughness

2.4

2.3

Specific Gravity

2.862.8-3

0 8.4

👆🏻

Transparency

Opaque

Density

2.8-2.9 g/cm³2.9-3.1 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

India, Russia

Africa

Namibia, Uganda

South Africa

Europe

Germany, Hungary, Italy, Portugal, Spain

Iceland

Others

Deposits in Western Continents

North America

USA

Canada, USA

South America

Brazil

Deposits in Oceania Continent

Australia

New Zealand, Western Australia

All about Tephrite and Variolite Properties

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