The amphiboles are a group of chain silicate minerals with some substitution of F and Cl for OH. They have a general formula of (W,X,Y)7-8(Z4O10)2(OH)2 where W represents large cations like Ca and Na, X represents smaller cations like Mg and Fe2+, Y represents Fe3+, Ti, and Al, and Z represents Si and Al. Amphiboles have elongate prismatic crystals and two prismatic cleavages that meet at 124 degrees, whereas pyroxenes have squat prisms and cleavages that meet at 88 degrees. Common amphiboles include hornblende, tremolite, actinolite
Introduction; Chemical composition of garnet; Structure; Classification; Physical properties; Optical properties; Occurrences; Gem variety; and Uses
Garnet group of minerals is one of the important group of minerals.
Since they are found in wide variety of colours, they are also used as gemstones.
Garnet group of minerals are also abrasives and thus have various industrial applications.
Introduction; Chemical composition of garnet; Structure; Classification; Physical properties; Optical properties; Occurrences; Gem variety; and Uses
Garnet group of minerals is one of the important group of minerals.
Since they are found in wide variety of colours, they are also used as gemstones.
Garnet group of minerals are also abrasives and thus have various industrial applications.
Komattite
Named after the Komati River in South Africa.
first described by Morris and Richard (twins) for ultramafic units in the Barberton Greenstone belt of South Africa.
Mostly of komatiite are Archean age
distributed in the Archaean shield areas.
Also a few are Proterozoic and Phanerozoic.
In all ages komatiites are highly magnesium.
Mostly a volcanic rock; occasionally intrusive.
Mafic rocks were identified as extrusive because of their volcanic textures and structures, and they seem to have been accepted as a normal component of Archean volcanic successions, Abitibi in Canada.
The ultramafic rocks were interpreted as intrusive which are founded as sills and dykes, Barberton in South Africa.
Spinifex texture-typical of Komatiites:
The current ppt discusses the different types of lineations formed due to deformation.
Lineations are genetically related to the foliation planes on which they occur, particularly where both are shaped by mineral orientations. Therefore, the planar and linear fabrics are both together aspects of the same three-dimensional geometry, which is related to the shape of the finite strain ellipsoid or,
more important still, to the history of incremental strains.
Mineral adalah zat padat berupa bahan an-organik yang terbentuk secara alamiah berupa unsur atau persenyawaan dengan komposisi kimia tertentu dan umumnya mempunyai struktur kristal tertentu yaitu bentuk-bentuk geometris beraturan.
Komattite
Named after the Komati River in South Africa.
first described by Morris and Richard (twins) for ultramafic units in the Barberton Greenstone belt of South Africa.
Mostly of komatiite are Archean age
distributed in the Archaean shield areas.
Also a few are Proterozoic and Phanerozoic.
In all ages komatiites are highly magnesium.
Mostly a volcanic rock; occasionally intrusive.
Mafic rocks were identified as extrusive because of their volcanic textures and structures, and they seem to have been accepted as a normal component of Archean volcanic successions, Abitibi in Canada.
The ultramafic rocks were interpreted as intrusive which are founded as sills and dykes, Barberton in South Africa.
Spinifex texture-typical of Komatiites:
The current ppt discusses the different types of lineations formed due to deformation.
Lineations are genetically related to the foliation planes on which they occur, particularly where both are shaped by mineral orientations. Therefore, the planar and linear fabrics are both together aspects of the same three-dimensional geometry, which is related to the shape of the finite strain ellipsoid or,
more important still, to the history of incremental strains.
Mineral adalah zat padat berupa bahan an-organik yang terbentuk secara alamiah berupa unsur atau persenyawaan dengan komposisi kimia tertentu dan umumnya mempunyai struktur kristal tertentu yaitu bentuk-bentuk geometris beraturan.
Nesosilicates or orthosilicates, have the orthosilicate ion, which constitute isolated (insular) [SiO4]4- tetrahedra that are connected only by interstitial cations. The atomic packing of the nesosilicate structure is generally dense which causes the mineral of this group to have relatively high specific gravity and hardness. The crystal habit of thee mineral is generally equidimensional and they have poor cleavage. The simplest structure in nesosilicates have mineral forsterite Mg2[SiO4]. These properties also that nesosilicates incorporate a considerable number of gemstones.
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