Alforsite
A variety of Minerals
What is Alforsite?
Alforsite is a barium phosphate chloride mineral with formula: Ba5(PO4)3Cl. It was discovered in 1981, and named to honor geologist John T. Alfors (1930–2005) of the California Geological Survey for his work in the area where it was discovered. Alforsite is a hexagonal colorless crystal in the chemical class phosphates and the group apatite. It is found in certain parts of central California, primarily Fresno, Mariposa, and Tulare Counties. It has also been found in Baja California, Mexico. Alforsite is a constituent of the apatite group of minerals. It crystallizes in the hexagonal crystal system with a point group of 6/m and space group P63/m. It occurs as colorless grains that are hard to distinguish from fluoroapatite, as they both display low birefringence and high relief.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Alforsite 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.
Alforsite Localities Map
See where Alforsite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Characteristics of Alforsite
Alforsite occurs as colorless, minuscule subhedral grains with a diameter less than 0.05 mm. However, on rare occasions, it can crystallize to a diameter up to 0.2 mm. Minerals that belong to different groups, such as silicates, and sulfates exhibit the structural typology of apatite. This can pose problems and confusion because alforsite bears an almost exact resemblance to other barium silicates, which exemplifies its group Greek name, apatao, meaning, “I am misleading”. The only way to differentiate alforsite from other barium minerals is through microchemical analysis (Walstrom and Leising, 2005). This misleading mineral emulates the physical and structural features of apatite and is analogously similar to chlorapatite, providing alfrosite with the alternate name, barium chlorapatite. Alforsite has a low birefringence and a high relief resembling fluorapatite in thin-section. A reddish-violet cathodoluminescence appears on thin-section showing major levels of chlorine, phosphorus, and barium. Alforsite can be recognized by electron microprobe analysis or by intense violet fluorescence in the 10-15 kV electron beam of a luminoscope
Composition of Alforsite
Alforsite's ideal chemical formula is Ba5(PO3)4Cl. Chemical analysis of the composition of alfrosite was demonstrated by the use of an Ortex current digitizer and an electron microbe. Synthetic barium chlorapatite, strontianite, and fluorapatite were used as standards for the elements they contain. The chemical analysis revealed that traces of Mn, S, Si, and Pb were present and provided computational formulas of (Ba4.68Sr0.19Ca0.13)(P2.98Si0.01)O11.96(Cl0.99F0.05) and (Ba4.05Ca0.75Sr0.24Pb0.03)(P2.94Si0.01)O11.93(Cl0.93F0.14).
Quick Facts
Physical Properties
- Color
- Colorless
- Hardness (Mohs)
- 5
- Density
- 4.8 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- Ba5(PO4)3Cl
- Elements
- Ba, Cl, O, P
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Alforsite FAQs
How do I identify Alforsite?
Alforsite can be identified by its hardness of 5 on the Mohs scale, Colorless color. Look for these key characteristics when examining specimens.
What color is Alforsite?
Alforsite typically appears in Colorless. Color can vary depending on impurities and formation conditions.
How hard is Alforsite?
Alforsite has a hardness of 5 on the Mohs scale. This gives it moderate hardness.
What is the characteristics of alforsite of Alforsite?
Alforsite occurs as colorless, minuscule subhedral grains with a diameter less than 0.05 mm. However, on rare occasions, it can crystallize to a diameter up to 0.2 mm. Minerals that belong to different groups, such as silicates, and sulfates exhibit the structural typology of apatite. This can pose problems and confusion because alforsite bears an almost exact resemblance to other barium silicates, which exemplifies its group Greek name, apatao, meaning, “I am misleading”. The only way to differentiate alforsite from other barium minerals is through microchemical analysis (Walstrom and Leising, 2005). This misleading mineral emulates the physical and structural features of apatite and is analogously similar to chlorapatite, providing alfrosite with the alternate name, barium chlorapatite. Alforsite has a low birefringence and a high relief resembling fluorapatite in thin-section. A reddish-violet cathodoluminescence appears on thin-section showing major levels of chlorine, phosphorus, and barium. Alforsite can be recognized by electron microprobe analysis or by intense violet fluorescence in the 10-15 kV electron beam of a luminoscope
What is the composition of alforsite of Alforsite?
Alforsite's ideal chemical formula is Ba5(PO3)4Cl. Chemical analysis of the composition of alfrosite was demonstrated by the use of an Ortex current digitizer and an electron microbe. Synthetic barium chlorapatite, strontianite, and fluorapatite were used as standards for the elements they contain. The chemical analysis revealed that traces of Mn, S, Si, and Pb were present and provided computational formulas of (Ba4.68Sr0.19Ca0.13)(P2.98Si0.01)O11.96(Cl0.99F0.05) and (Ba4.05Ca0.75Sr0.24Pb0.03)(P2.94Si0.01)O11.93(Cl0.93F0.14).
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