Rameauite
| Rameauite | |
|---|---|
| General | |
| Category | Oxide mineral |
| Formula (repeating unit) | K2Ca(UO2)6OH16·H2O or K2CaU6+6O20·9(H2O) |
| Crystal system | Monoclinic |
| Space group | Monoclinic |
| Unit cell | a= 13.97, b= 14.26, c= 14.22 Å, β = 121.02° |
| Identification | |
| Formula mass | 2,028.57 g |
| Color | Orange |
| Crystal habit | Prismatic and/or can consist of a hexagonal outline |
| Cleavage | Good cleavage |
| Diaphaneity | Semitransparent |
| Density | 5.6 |
| Optical properties | Biaxial Negative |
| Refractive index | a= n.d. β= 1.95 γ= 1.97 |
| 2V angle | 32° (meas.) |
| References | [1][2][3] |
Rameauite is a uranium oxide mineral with formula K2Ca(UO2)6OH16·H2O[4] or K2CaU6+6O20·9(H2O).[3]
It was first described in 1972 for an occurrence in the Margnac Mine, Compreignac, Haute-Vienne, Limousin, France and named for Jacques Rameau (?-1960), the French prospector who discovered the deposit.[4][3]
Rameauite consist of small crystals that are orange and are typacally with calcite and ex-uranophane. These are all on a block of pitchblende. Rameauite has 4 observed forms which are {010}, {100}, {001},and {110}. The measurments of those forms are {100}={001} = 58°40' and {010}={110} = 49° 50'. Other observations are that along {100} the crystals are all twinning, and along {010} they are kind of flattened parallel to it, and along {001} they are elongated parallel to it. The mineral Rameauite is an example of a Monoclinic mineral and is also pseudo-hexagonal that consist of these measurments: a= 13'97, b= 14'26, c= 14'22. [5][3]
Since Rameauite is monoclinc, that means that the three axes it has are all unequal in length as shown in the sentence before this given as a,b and c. Also, being mononclic tells us that Rameauite is biaxel which means that this mineral has 2 optic axes. The refraction index is show on the table to the right; Rameauite has a total of 3. This tells us the measure of the speed of light in the mineral.[5][3] Looking at the refractive index, we can also tell the relief of Rameauite, which is high. Relief is how easily you can see a mineral grain under a microscope. Having high relief means that the border around the grain is dark and easily spotted; as in Rameauite's case. [6][3]
References
- ^ http://webmineral.com/data/Rameauite.shtml
- ^ http://un2sg4.unige.ch/athena/cgi-bin/minfich?s=Rameauite
- ^ a b c d e f Handbook of Mineralogy
- ^ a b Mindat.org
- ^ a b [1] Cite error: The named reference "geo.arizona" was defined multiple times with different content (see the help page).
- ^ [2]
- Cesbron, F., W.L. Brown, P. Bariand, and J. Geffroy (1972) Rameauite and agrinierite, two new hydrated complex uranyl oxides from Margnac, France. Mineralogical Magazine, 38, 781–789.