| 词条 | Oneillite |
| 释义 |
| name = Oneillite | category = Silicate mineral, Cyclosilicate | image = | imagesize = | alt = | caption = | formula = Na15Ca3Mn3Fe3Zr3Nb(Si25O73)(O,OH,H2O)3(OH,Cl)2 (original form) | strunz = 9.CO.10 | dana = | system = Trigonal | class = Pyramidal (3) H-M symbol: (3) | symmetry = R3 | unit cell = a = 14.19, c = 29.98 [Å], Z = 3 (approximated) | color = Yellowish brown | colour = | habit = anhedral grains | twinning = | cleavage = None | fracture = Uneven | tenacity = Brittle | mohs = 5-6 | luster = Vitreous | streak = White | diaphaneity = Transparent or translucent | gravity = | density = 3.20 g/cm3 (measured) | polish = | opticalprop = Uniaxial (-) | refractive = nω=1.65 nε=1.64 (approximated) | birefringence = | pleochroism = None | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = [1][2] }}Oneillite is a rare mineral of the eudialyte group with the formula Na15Ca3Mn3Fe2+3Zr3NbSiO(Si3O9)2(Si9O27)2(O,OH,H2O)3(OH,Cl)2.[1][2] The formula is based on the original one but extended to show the presence of cyclic silicate groups and domination of Si at the M4 site. The mineral has lowered symmetry (space group R3, instead of more specific for the group R3m one) due to Ca-Mn ordering.[1] Similar feature is displayed by some other eudialyte-group members: aqualite, labyrinthite, raslakite, and voronkovite.[2] Oneillite is strongly enriched in rare earth elements (REE, mainly cerium), but REE do not dominate any of its sites.[1] Notes on chemistryRare earth elements in oneillite include cerium, lanthanum, neodymium, and yttrium, with minor praseodymium and gadolinium. Other impurities are potassium, and minor amounts of aluminium, hafnium, strontium and tantalum.[1] Occurrence and associationOneillite is one of four eudialyte-group minerals discovered within alkaline rocks of Mont Saint-Hilaire, Quebec, Canada. It associates with aegirine, albite, sodalite, and pyrite.[1] References1. ^1 2 3 4 5 Johnsen, O., Grice, J.D., and Gault, R.A., 1999. Oneillite: a new Ca-deficient and REE-rich member of the eudialyte group from Mont Saint-Hilaire, Quebec, Canada. The Canadian Mineralogist 37, 1295-1301 {{silicate-mineral-stub}}2. ^1 2 Mindat, Oneillite, http://www.mindat.org/min-11029.html 8 : Cyclosilicates|Sodium minerals|Calcium minerals|Manganese minerals|Iron minerals|Zirconium minerals|Niobium minerals|Trigonal minerals |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。