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records of Chlorophaeite occurrence is no always constant due to loosely use of the term ( citation). Frist appeared at the Giant’s causeway recorded in the manual of mineralogy (need cite). Chlorophaeite is formed as a product of carboniferous decomposition of the rock (cite). Chlorophaeite from different regions displays identical features. occurrence is spread out through out

this is an article about a mineral

Description
Chlorophaeite is a well recognisable naturally occurring, homogenous, amorphous substance, found in basalts fills or enclosed in volcanic acid glass mainly (Weaving 1962), MacCulloch (1819) first used this term to describe this mineral which display colour change, first exhibits a dull greenish brown, once upon rapaid exposure to air substance changes colour from dark green to black with glossy texture.Upon prolonged exposed to air mineral become a orange to dark brown colour (peacock 1928, peacock 1930, strokes 1971). no change need!

A fresh large rock form specimen with hardness between 1.5-3, discovered in Columbia river plateau in Washington displays a dark, compact, medium-grained primary mineral in which only small fragments are recognisable (peacock 1928). Fragments collected from rock surfaces (peacock 1928) shown many circular spherical bodies, sections constitute of 10% of the bulk of the rock with an average of 5mm, shown in broken rock surface, a few of the spherical bodies have quartz or calcite filling, while majority consist of black minerals (Fermor 1931, peacock 1928).

Analysis of derived mineral composition form close association to the description of coarser rock type. With observed low silica content and with simliar alkalic like characteristic (Fermor 1931, peacock 1928)[1].Cholorphaeite occurs as isotopic form, often present in orange dark brown colour in small patches, thin vein like form, in cavities fillings [6],with a lower refractive index than balsam (Fermor 1931, peacock 1928). Under unfrequented conditions veinlets can form up to relatively long (upto inches) and thicker veinlets. Samples crashed into small grains are examined, varying in refractive indices, from below 1.498 to 1.540, with the average value of 1.530 (peacock 1928). Small cracks developed within fine nets inside the cholorphaeite, due to existing fine networks of cracks, as well as reacting with hydrochloridc acid leaving a gel like silica material initiate crystallisation, result in Irregular double refraction mineral forming in spherical form with fine fibres developed (Fermor 1931, peacock 1928). larger patches of the mineral surface covered in projections, internal sturcture is covered by layer of coating.

Analysis of chlorophaeite from Scotland and India represents qualitative reliable data of the mineral constitutes, mineral is usually covered in microorganism like micro tubiform bodies.(peacock 1928). Chlorophaeite deposits, occurs as irregular films distributed throughout rock surface, mostly consist clear rectangular shaped pyroxene pseudomorphs (Fermor 1931, peacock 1928). Due to the additional of brown chlorophaeite pseudomorph presence, making other minerals present on the rock body more susceptible to alteration. Rhombus shaped pyroxenes are susceptible to alteration, the presence of chlorophaeite pseudomorph altered rhombic pyroxenes form and the chemical composition (Fermor 1931, peacock 1928). When the mineral is altered the composition is completely replaced by carbonate, with tubiform bodies still visible.

The striking colour change caused by exposure to air differentiate chlorophaeite from other chlorite minerals. A fresh rock sample containing large quantity of chlorophaeite is broken into small chip, placed under direct sunlight in the presence of oxygen pale-green colour is first observed, within fifteen minutes upon exposure to atmosphere colour rapidly changes to dark green, then under ninety minute changes to an shiny black opaque colour, with dark brown translucency shown at thin edge, long exposure to air results in colour loss of glossy texture (#6,Peacock 1928). this rapid change is considered as a physical molecular change due to oxidisation, whilst exposure to sunlight did not alter the colour of the mineral. The process of colour change can be delayed without exposure to oxygen The chip can be easily crashed into finer powdered form (Peacock 1928). When mineral is exposed to conditions with only the presence of carbon dioxide colour change was hardly observed. further colour change from green to black was induced by artificial heating of a fragment sample with flame, under prolonged heating, a reddish brown colour is observed simulating the natural colour of the mineral on rock surface under weathering. pale-green colour is retained under non-oxidising condition.

Based on the minerals amosphrous property, hardness, refractive index as well as the chemical composition excluding the likelihood of this mineral to be glass, with scaly and infrequently spherical in shape[8]. According mineral chemcial and physical properties, suggested that chlorophaeite is isotropic display characteristics of a colloid, with prersence of micro-organisms like structure correlated to the presence of artificial gel. with occasional bi-refraction property displays similarities characteristics to most gel like sturctures, chlorophaeite is not considered a crystalline mineralconsisting high amount of water with variations in water content accroding to tempurature changes.

Due to nature of this mineral, it is less susceptible to magnification when present in normal state in the atmosphere, possibly due to lack of magnetic content (Meyer 1978). Sample and natural rock from different regions containing chlorophaeite all displays similar changes in magnetic field through heating (Meyer 1978). Rock magnetic stability is met when the thermoremanent moment change in accordingly to heating temperature, with no change in mineral stability, magnetic stability can not be met for rocks which contains chlorophaeite particularly during heating at high temperature (600 degrees), the mineral becomes a more magnetic form, with changed magnetic properties (Weaving 1962). Most noticeable increase in magnetism is observed when heated in sealed, reducing atmosphere, compare to a slight slower rate of magnification when heated under oxidizing conditions (Fermor 1931, peacock 1928). After heating, cholorpaeite become magnetic exhibits in crumbled form (Fermor 1931, peacock 1928).Chlorophaeite display a black and reddish iron ore like form, with time, rate of magnification can be changed by ageing of the mineral (Fermor 1931, peacock 1928).

mineral composition and chemical properties
chemical formula for chlorophaeite

(Ca,Mg,Fe)2Fe2Si4O13 · 10H2O (Mindat.org 2019)

Chlorophaeite of different origins have approximately precise chemical properties (Weaving 1962) contains proportions of ferric and ferrous oxides (Fermor 1931)

formation and occurrences
Chlorophaeite is related to chlorite due to its characteristics, occurs in basalts and dolerite of the mineralrites rocks by the reaction of ferromagnesian minerals with magmatic fluids, sometimes with ultra-basic vitreous residue but mostly occur as psedomorph (Peacock 1930)

3 forms of occurrence

Found In a 55 feet thick dike cavity filling, cutting Columbia River Basalt in the Grande Ronde Valley southeast Washington (Fermor 1931, Peacock 1930, Stokes 1971).occurs in basalts and dolerites rocks by the reaction of ferromagnesian minerals with magmatic fluids, sometimes with ultra-basic vitreous residue but mostly around altered olivine grains (Peacock 1930), similar occurrence in basalt vesicular fillings in Northern Ireland (Weaving 1962)

Occurs as globules present in many Iceland dikes as rock filling, spherical shaped, occurs in association with interstitial galss, encased by igneous volcanic glass with no crystal structure, derived product of basalts due to loss in composition, density. (Meyer 1978)

Chlorophaeite occurs in “ interstitial phase” as vesicle fillings, exhibits features very similar to an concentric core of isotropic material with drying cracks, anisotropic material for rims of radiating fibrous product (Meyer 1978, stokes 1971).

Geographic distribution
Occurrence of mineral around America, Australia, Iceland, India, UK and Columbia river plateau, Giant’s Causeway in manual of mineralogy (citation). Originally discovered in Isle of Rhum, as well as in the royal Burgh, North West Highlands of Edinburgh, chlorophaeite is also found distributed throughout different areas around Scotland, UK (Fermor, 1931, Peacock, 1930, Stokes, 1971).