Hornfels

Picrite

Hornfels and Picrite

Hornfels

Picrite

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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

Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine

History

Origin

New Zealand

Hawaii Islands

Discoverer

Unknown

Etymology

From German which means hornstone

From Greek pikros bitter + -ite, 19th century

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

Texture

Granular, Platy

Earthy, Rough

Color

Brown, Dark Greenish - Grey, Green, Reddish Brown

Black, Brown, Green, Grey, Pink, White, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Rough and Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Flooring, Homes, Interior Decoration

Countertops, Decorative Aggregates, 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, Paving Stone

Other Architectural Uses

Curbing

Industry

Construction Industry

for Road Aggregate, Roadstone

As a Sintering Agent in Steel Industry to process Iron Ore, Cement Manufacture, for Road Aggregate, Manufacture of Magnesium and Dolomite Refractories, Roadstone, Used for flooring, stair treads, borders and window sills.

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Cemetery Markers, Commemorative Tablets, Creating Artwork

As a Feed Additive for Livestock, As armour rock for sea walls, Metallurgical Flux, Pottery, Source of Magnesia (MgO)

Types

Biotite hornfels

Oceanite

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.

Picrite 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

Biotite, Olivine, Plagioclase, Pyrrhotite

Compound Content

Fe, Mg

Al, CaO, Carbon Dioxide, Mg, MgO

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological 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, Wind Erosion

Properties

Physical Properties

Hardness

2-36.8

1 7

👆🏻

Grain Size

Fine Grained

Fracture

Conchoidal

Uneven

Streak

White, Greenish White or Grey

Porosity

Highly Porous

Less Porous

Luster

Shiny

Subvitreous to Dull

Compressive Strength

5.80 N/mm²189.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

2.1

Specific Gravity

3.4-3.92.75-2.92

0 8.4

👆🏻

Transparency

Opaque

Density

0.25-0.30 g/cm³1.5-2.5 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.84 kJ/Kg K0.88 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

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

India, Russia

Africa

Cameroon, East Africa, Tanzania, Western Africa

South Africa

Europe

United Kingdom

Iceland

Others

Deposits in Western Continents

North America

Canada, USA

South America

Bolivia, Brazil, Colombia, Ecuador

Brazil

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Western Australia

All about Hornfels and Picrite Properties

Know all about Hornfels and Picrite properties here. All properties of rocks are important as they define the type of rock and its application. Hornfels belongs to Metamorphic Rocks while Picrite belongs to Igneous Rocks.Texture of Hornfels is Granular, Platy whereas that of Picrite is Earthy, Rough. Hornfels appears Dull and Picrite appears Rough and Shiny. The luster of Hornfels is shiny while that of Picrite is subvitreous to dull. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas Picrite is available in black, brown, green, grey, pink, white, yellow colors. The commercial uses of Hornfels are cemetery markers, commemorative tablets, creating artwork and that of Picrite are as a feed additive for livestock, as armour rock for sea walls, metallurgical flux, pottery, source of magnesia (mgo).