Chlorite group of mineral

CHLORITE GROUP

• Derived from greek word chlorous which means green.

• The chlorites are a group of of phyllosilicate minerals.

• Chlorite group devoid alkali metals and rich in ferrous iron.

• Chlorite mineral are monoclinic crystal system.• They possess a perfect cleavage.

CHLORITE GROUP

Chemical formula :- (Mg,Fe,Li)6AlSi3O10(OH)8

Colour :- Green Streak :- Green,Brown Cleavage :- Perfect Fracture :- Flexible Hardness :- 2 to 2.5 Specific Gravity :- 3 Transparency :- Transparent

Physical properties :-

Optical property of Chlorite :- • Pleochroism :- Yellow- green – brown• Colour :- Green,greenish brown• Relief:- Moderate to high• Birefrenges :- Low• Interference Colour :- Anomalous blue,1st order yellow,brown,purple• Crystal System :- Monoclinic• Habit :- Chlorite has habit similar to the other

micas;foliated book and individual flakes in a quartz-feldspar matirx are common

Members of the chlorite group :-Baileychlore (Zn,Fe+2,Al,Mg)6(Al Si)4O10(O,OH)8

Chamosite (Fe , Mg)5Al(Si3Al)O10(OH)8

Clinochlore (Mg,Fe2+)5Al(Si3Al)O10(OH)8

Cookeite LiAl4(Si3Al)O10(OH)8

Donbassite Al2[Al2.33][Si3AlO10](OH)8

Gonyerite (Mn,Mg)5(Fe+3)2Si3O10(OH)8

Nimite (Ni,Mg,Al)6(Si,Al)4O10(OH)8

Odinite (Fe,Mg,Al,Fe,Ti,Mn)2.4(Al,Si)2O5OH4

Orthochamosite (Fe+2,Mg,Fe+3)5Al(Si3Al)O10(O,OH)8

Pennantite (Mn5Al)(Si3Al)O10(OH)8

Ripidolite (Mg,Fe,Al)6(Al,Si)4O10(OH)8

Sudoite Mg2(Al , Fe)3Si3AlO10(OH)

MOST COMMON MEMBER OF CHLORITE GROUP :-

Clinoclore ( Magnesiun (Mg)-rich chlorite) Chamosite (Iron (Fe)-rich chlorite) Nimite (Nickel (Ni) -rich chlorite) Pennantite (Manganese (Mn) -rich chlorite)

CLINOCHLORE • Clinochlore is a member of the Chlorite group and is one of

the better-known members. It most often is an uninteresting matrix for more important minerals, but the rare and beautiful pink to red variety. Kammererite is very popular and treasured by collectors.

Clinochlore forms a series with the Chamosite within the Chlorite group. Chamosite is the iron rich end member, and Clinochlore is the magnesium-rich end member. Their properties are very similar, and they are difficult to distinguish from each other, though Clinochlore is softer, lighter, and usually more transparent than Chamosite

Physical property of Clinochlore

• Chemical formula :- (Mg5Al)(AlSi3)O10(OH)8

• Colour :- Pink red purple yellow grey brown• Streak :- White• Cleavage:- Perfect• Fracture :- Uneven• Crystal System :- Monoclinic• Hardness :- 2-2.5• Specific Gravity :- 2.5-3• Lusture :- Vitreous to pearly • Transparency :- Transparent to translucent

Image of Clinochlore

Foliate Clinochlore Sheet

CHAMOSITE

• Chamosite is a member of the Chlorite, and it forms a series with the mineral Clinochlore

• Chamosite is the iron rich end member, and Clinochlore is the magnesium-rich end member.

• Their properties are very similar, and they are difficult to distinguish from each other, though Chamosite is harder, heavier, and usually less transparent than Clinochlore.

Physical property of Chamosite :-

• Chemical formula :- (Fe,Mg)5Al(Si3Al)O10(OH)8

• Colour :- Greenish-grey , grey, greenish-black• Streak :-White• Cleavage :- Perfect• Fracture :- Uneven• Hardness :- 2.5-3• Specific Gravity :- 3-3.4• Crystal System :- Monoclinic• Lusture :- Vitreous to pearly• Transparency :-Translucent

Image of Chamosite

NIMITE

Physical property of Nimite :-

• Chemical formula :-(Ni,Mg,Al)6(Si,Al)4O10(OH)8

• Colour :- Yellow green• Streak :-White• Cleavage :- Perfect • Fracture :- Uneven• Hardness :- 3• Specific Gravity :- 3-3.4• Crystal System :- Monoclinic• Lusture :- Vitreous to pearly• Transparency :-Translucent

Pennantite

Physical property of Pennantite :-

• Chemical formula :- (Mn5Al)(Si3Al)O10(OH)8

• Colour :- Red,brown, dark -green,black • Cleavage :- Perfect• Fracture :- Uneven• Hardness :- 2-2.5• Specific Gravity :- 3-3.4• Crystal System :- Monoclinic• Lusture :- Vitreous to pearly• Transparency :-Translucent

OCCURRENCE :-

• Chlorite is a common mineral in low grade metamorphic rocks, such as chlorite schist.

• In igneous rock, chloriteis mostly a secondary mineral,forming from the hydrothermal breakdown of pyroxene,amphibole and boitite.

• Chlorites are common in argillaceous sedimentary rocks, where they occur with clay minerals.

Uses of Chlorite• Chlorite is a mineral with a low potential for industrial use. • It does not have physical properties that make it suited for

a particular use, and it does not contain constituents that make it a target of mining.

• When found, chlorite is usually intimately intermixed with other minerals, and the cost of separation would be high.

• Chlorite is not mined and processed for any specific use. Its major use is as a coincidental constituents in crushed stone.

Distinguishing from other minerals

• Chlorite is so soft that it can be scratched by a finger nail. The powder generated by scratching is green. It feels oily when rubbed between the fingers.

• The plates are flexible, but not elastic like mica.

Reference :-

• Rutley’s elements of mineralogy.• Internet

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