Chamosite
A variety of Minerals
What is Chamosite?
Chamosite is the Feend member of the chlorite group. A hydrous aluminium silicate of iron, which is produced in an environment of low to moderate grade of metamorphosed iron deposits, as gray or black crystals in oolitic iron ore. Like other chlorites, it is a product of the hydrothermal alteration of pyroxenes, amphiboles and biotite in igneous rock. The composition of chlorite is often related to that of the original igneous mineral so that more Fe-rich chlorites are commonly found as replacements of the Fe-rich ferromagnesian minerals (Deer et al., 1992).
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Chamosite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Chamosite Localities Map
See where Chamosite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Characteristics of Chamosite
Chamosite has a laminar shape, sheets measure from 20 to 200 μm (Rivas Sanchez et al., 2006). Chamosite may be greenish gray or brown in color. The cleavage are length-slow, the orientation may be α ∧ c=small, β=b, γ ∧ α=small, optic plane= [0 10] (Heinrich, 1965) and has good cleavage on the {011} axis. It has a dull luster and grayish-green streak. Birefringence is much lower than that of the micas, illite, montmorillonite and vermiculite, and refractive indices are higher than those of kaolinite (Deer et al. 1992). The chamosite spectra shows the reflection d=7.18 Å (main value of the chlorite) and the reflection d=14.4 Å (that confirms the presence of chlorite) (Rivas Sanchez et al., 2006).
Composition of Chamosite
X-ray diffraction (XRD) indicates that the proportion of 7 Å B layers in bertherine-chamosite ranges from 5 to 28%, and chemical analysis by scanning electron microscope-energy-dispersive X-ray spectroscopy (SEM-EDS) indicates positive correlation between %B and Fe/(Fe + Mg) (Ryan and Hillier, 2002). The chamosite structure is very similar to typical chlorite in which they are alternated regular layers with tetrahedral and tri-octahedral components (Rivas Sanchez et al., 2006). Its 2:1 layer structure is similar to that of mica, with a basal spacing of 14 Å. (Rivas Sanchez et al., 2006). In most common chlorites, there are 12.0 octahedral cations per O20(OH)16 and approximately equivalent amounts of aluminium in tetrahedral and octahedral sites [e.g. the magnesia chlorite, clinochlore, (Mg10Al2)(Si6Al2O20)(OH)16] (Deer et al., 1992).
Quick Facts
Physical Properties
- Color
- Green, grey-green, black
- Hardness (Mohs)
- 3
Chemical Properties
- Chemical Formula
- (Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8
- Elements
- Al, Fe, H, Mg, O, Si
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Chamosite FAQs
How do I identify Chamosite?
Chamosite can be identified by its hardness of 3 on the Mohs scale, Green color. Look for these key characteristics when examining specimens.
What color is Chamosite?
Chamosite typically appears in Green, grey-green, black. Color can vary depending on impurities and formation conditions.
How hard is Chamosite?
Chamosite has a hardness of 3 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the characteristics of chamosite of Chamosite?
Chamosite has a laminar shape, sheets measure from 20 to 200 μm (Rivas Sanchez et al., 2006). Chamosite may be greenish gray or brown in color. The cleavage are length-slow, the orientation may be α ∧ c=small, β=b, γ ∧ α=small, optic plane= [0 10] (Heinrich, 1965) and has good cleavage on the {011} axis. It has a dull luster and grayish-green streak. Birefringence is much lower than that of the micas, illite, montmorillonite and vermiculite, and refractive indices are higher than those of kaolinite (Deer et al. 1992). The chamosite spectra shows the reflection d=7.18 Å (main value of the chlorite) and the reflection d=14.4 Å (that confirms the presence of chlorite) (Rivas Sanchez et al., 2006).
What is the composition of chamosite of Chamosite?
X-ray diffraction (XRD) indicates that the proportion of 7 Å B layers in bertherine-chamosite ranges from 5 to 28%, and chemical analysis by scanning electron microscope-energy-dispersive X-ray spectroscopy (SEM-EDS) indicates positive correlation between %B and Fe/(Fe + Mg) (Ryan and Hillier, 2002). The chamosite structure is very similar to typical chlorite in which they are alternated regular layers with tetrahedral and tri-octahedral components (Rivas Sanchez et al., 2006). Its 2:1 layer structure is similar to that of mica, with a basal spacing of 14 Å. (Rivas Sanchez et al., 2006). In most common chlorites, there are 12.0 octahedral cations per O20(OH)16 and approximately equivalent amounts of aluminium in tetrahedral and octahedral sites [e.g. the magnesia chlorite, clinochlore, (Mg10Al2)(Si6Al2O20)(OH)16] (Deer et al., 1992).
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