Dacite

Gneiss

Dacite and Gneiss

Dacite

Gneiss

Add ⊕

Definition

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

Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks

History

Origin

Romania and Moldova, Europe

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 the Middle High German verb gneist (to spark; so called because the rock glitters)

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

Coarse Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Aphanitic to Porphyritic

Banded, Foliated, Platy

Color

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

Black, Brown, Pink, Red, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Vesicular

Foliated

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Interior Decoration

Countertops, Decorative Aggregates, Flooring, Interior Decoration

Exterior Uses

As Building Stone, Paving Stone, Garden Decoration

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

Other Architectural Uses

Curbing

Industry

Construction Industry

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

As Dimension Stone

Medical Industry

Antiquity Uses

Artifacts

Other Uses

Commercial Uses

Commemorative Tablets, Creating Artwork

Cemetery Markers, Jewelry, Tombstones, Used in aquariums

Types

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.

Features

Host Rock for Lead, Is one of the oldest rock

Generally rough to touch, Is one of the oldest rock

Archaeological Significance

Monuments

Famous Monuments

Konark Sun Temple in India, Washington Monument, US

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.

Gneiss is a high grade metamorphic rock i.e. it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of Gneiss forms from volcanic rock, shale or granitie.

Composition

Mineral Content

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

Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon

Compound Content

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

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

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism

Impact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Biological Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

Properties

Physical Properties

Hardness

2-2.257

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Medium to Coarse Grained

Fracture

Conchoidal

Irregular

Streak

White

Porosity

Less Porous

Very Less Porous

Luster

Subvitreous to Dull

Dull

Compressive Strength

70.00 N/mm²125.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

1.2

Specific Gravity

2.86-2.872.5-2.7

0 8.4

👆🏻

Transparency

Translucent

Translucent to Opaque

Density

2.77-2.771 g/cm³2.6-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.70 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia

Africa

Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo

Europe

France, Greece, Romania, Scotland, Spain

Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Switzerland, Ukraine, United Kingdom

Others

Deposits in Western Continents

North America

USA

Canada, Costa Rica, Cuba, Mexico, Panama, USA

South America

Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela

Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela

Deposits in Oceania Continent

Australia

New Zealand, South Australia, Western Australia

New South Wales, New Zealand, Queensland, Victoria

All about Dacite and Gneiss Properties

Know all about Dacite and Gneiss properties here. All properties of rocks are important as they define the type of rock and its application. Dacite belongs to Igneous Rocks while Gneiss belongs to Metamorphic Rocks.Texture of Dacite is Aphanitic to Porphyritic whereas that of Gneiss is Banded, Foliated, Platy. Dacite appears Vesicular and Gneiss appears Foliated. The luster of Dacite is subvitreous to dull while that of Gneiss is dull. Dacite is available in bluish - grey, brown, grey, light to dark grey colors whereas Gneiss is available in black, brown, pink, red, white colors. The commercial uses of Dacite are commemorative tablets, creating artwork and that of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums.