Merrillite
| Merrillite | |
|---|---|
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) |
Ca9NaMg(PO4)7 |
| Strunz classification | 08.AC.45 |
| Crystal symmetry | Trigonal ditrigonal pyramidal H-M symbol: (3m) Space group: R 3c |
| Unit cell | a = 10.362 Å, c = 37.106 Å; Z=6 |
| Identification | |
| Color | Colorless to white |
| Crystal habit | Occurs as anhedral grains |
| Crystal system | Trigonal |
| Cleavage | Poor - indistinct |
| Tenacity | Brittle |
| Luster | Vitreous |
| Specific gravity | 3.1 (measured) |
| Optical properties | Uniaxial (-) |
| Refractive index | nε=1.62, nω=1.623 |
| Birefringence | 0.0030 |
| References | [1][2] |
Merrillite is a calcium phosphate mineral with the chemical formula Ca9NaMg(PO4)7. It is an anhydrous, sodic member of the whitlockite group.[2]
Discovery and naming
The mineral is named after George P. Merrill (1854–1929) of the Smithsonian Institution.[2] Merrill had described the mineral from four meteorites in 1915: the Alfianello, Dhurmsala, Pultusk, and Rich Mountain meteorites. The mineral was not recognized as distinct from whitlockite, however, by the IMA until 1975.[2]
Occurrence
Merrillite is a very important constituent of extraterrestrial rocks. It occurs in pallasites, lunar rocks, martian meteorites, and many other meteorite groups.[3]
References
<templatestyles src="Reflist/styles.css" />
Cite error: Invalid <references> tag; parameter "group" is allowed only.
<references />, or <references group="..." /><templatestyles src="Asbox/styles.css"></templatestyles>
