Hornfels

Tephrite

Hornfels and Tephrite

Hornfels

Tephrite

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Definition

Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat altered equivalent of the original rock

Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock

History

Origin

New Zealand

Germany

Discoverer

Unknown

Van Tooren

Etymology

From German which means hornstone

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

Class

Metamorphic Rocks

Igneous Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

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

Texture

Granular, Platy

Aphanitic to Porphyritic

Color

Brown, Dark Greenish - Grey, Green, Reddish Brown

Black, Brown, Green, Grey, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Vesicular

Uses

Architecture

Interior Uses

Decorative Aggregates, Flooring, Homes, Interior Decoration

Exterior Uses

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

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

Other Architectural Uses

Curbing

Industry

Construction Industry

for Road Aggregate, Roadstone

Landscaping

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts, Sculpture

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork

Production of Lime, Soil Conditioner

Types

Biotite hornfels

Igneous rock

Features

Smooth to touch

Host Rock for Lead

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Hornfels is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.

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

Andalusite

Alkali feldspar, Nepheline, Plagioclase, Pyroxene

Compound Content

Fe, Mg

CaO, Carbon Dioxide, MgO, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion

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

Properties

Physical Properties

Hardness

2-36.5

1 7

👆🏻

Grain Size

Fine Grained

Medium to Fine Coarse Grained

Fracture

Conchoidal

Uneven

Streak

Bluish Black

Porosity

Highly Porous

Very Less Porous

Luster

Shiny

Subvitreous to Dull

Compressive Strength

5.80 N/mm²90.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Crenulation and Pervasive

Toughness

2.4

Specific Gravity

3.4-3.92.86

0 8.4

👆🏻

Transparency

Opaque

Density

0.25-0.30 g/cm³2.8-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand

Africa

Cameroon, East Africa, Tanzania, Western Africa

Namibia, Uganda

Europe

United Kingdom

Germany, Hungary, Italy, Portugal, Spain

Others

Deposits in Western Continents

North America

Canada, USA

USA

South America

Bolivia, Brazil, Colombia, Ecuador

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Western Australia

New Zealand, Western Australia

All about Hornfels and Tephrite Properties

Know all about Hornfels and Tephrite properties here. All properties of rocks are important as they define the type of rock and its application. Hornfels belongs to Metamorphic Rocks while Tephrite belongs to Igneous Rocks.Texture of Hornfels is Granular, Platy whereas that of Tephrite is Aphanitic to Porphyritic. Hornfels appears Dull and Tephrite appears Vesicular. The luster of Hornfels is shiny while that of Tephrite is subvitreous to dull. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas Tephrite is available in black, brown, green, grey, white colors. The commercial uses of Hornfels are cemetery markers, commemorative tablets, creating artwork and that of Tephrite are production of lime, soil conditioner.