Topic: ArtPottery

Last updated: March 11, 2019

Type of Rock Sedimentary Rock: Gypsum Picture of gypsum Sketching of gypsumRock Identification Gypsum rock have inconsistent jiggered rough appearance. Accumulation of gypsum mineral create gypsum rock and naturally gypsum rock are white in colour. However, different impurities that combined together to form gypsum rock may give a range of various colours to the rock. Description of gypsum:Type Name Cleavage Colour Lustre Hardness Specific GravityM456 Gypsum Have cleavage White or grey in colour Vitreous to silky 2 2.33Characteristics Features and Physical Properties Gypsum is a soft and considerably less in weight mineral that have quite a fast rate of solubility in water. Gypsum is originally white or grey in colour but in some occurrences, its colour of appearance can also become green, pink, yellow and brown due to addition of impurities in the formation.

Gypsum crystal have good flexibility but once they are stretched to one certain length ,they will not return to original shape and will maintain the stretched form. Mode of Formation and Occurrence Rock gypsum will be formed when concentrated solutions like seawater evaporated. Hence gypsum rock are abundant at places with high evaporation rate such as at desert lakes and marine region. At desert, formation of gypsum crystals is called as “desert rose” formation as it take the form petals of flower during formation.Similar rocks and minerals Gypsum is sometimes confused with anhydrite.

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Both gypsum and anhydrite share an approximate appearance which is they are commonly exist in white colour. Gypsum can be related to bassanite in term of chemical composition. Both gypsum and bassanite contain hydrous calcium sulphate, however, gypsum(CaSO4·2H2O) contains more water compare to bassanite (CaSO4·0.5H2O) Gypsum is widely used manufacture of wallboard, cement, plaster of Paris, soil conditioning, and a hardening retarder in Portland cement. Usage of gypsum in construction is rather wide due to its eco-friendly properties. Study shown that gypsum construction products have enhance properties in flexure and thermal conductivity.Type of Rock Sedimentary rock: Shale Photo of shale Sketching of shale Rock Identification Shale rock is the most abundant sedimentary rock on Earth.

It have laminated appearance and usually formed in sheets. Shale is also one of the fine-grained rock and consists of silt and clay sized particles. Shale are made up of 30% clay, minerals and large amount of quartz. It also have small amount of carbonates, feldspar and organic matters Description of quartz:Type Name Cleavage Colour Lustre Hardness Specific GravityM286 Quartz Indistinct No colour Vitreous 7 2.65Characteristics Features and Physical Properties Shale have tendency to break into thin layers which usually will be parallel to plane surface. Shale also have properties of plasticity and permeability. Shale have very tiny pores known as nanopores inside its structure.

Shale will have darker colour when the organic content in it is high. Hematite and limonite will make shale to appear reddish and purple in colour. Mode of Formation and Occurrence Shale forms as a result of compaction and cementation of materials that eroded from pre-existing rocks. Compaction and cementation of clay minerals and silicates will eventually form shale. Shales are usually deposited and can be found at places with very slow flowing water such as lakes, river deltas, and sedimentary basins.Similar rocks and minerals Most of the time, shale are being confused with slate. Both stone have very little difference in terms of appearance and one cannot directly distinguish these two type of rocks by just visually examined it. Slate is metamorphic rock that formed from shale that exposed to pressure and heat.

In terms of mineral similarity, shale can be related to schist. Schist is a metamorphic rock that formed through metamorphosis process. Study revealed that schist parent rock was shale which mean shale rock that undergo metamorphosis will end up become schist. Since schist was once shale rock, their mineral composition is almost the same.Shale are widely used for applications in the ceramics industry. Shale are very important raw material to manufacture tile brick and pottery.

Organic-rich shales known as oil shales that contain kerogen(a complex mixture of solid hydrocarbons derived from plant and animal matter) are currently being study to turn it into practical source for liquid petroleum


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