Scandiobabingtonite
| Scandiobabingtonite | |
|---|---|
| General | |
| Category | Inosilicate |
|
Formula (repeating unit) |
Ca2(Fe2+, Mn)ScSi5O14(OH) |
| Strunz classification | 9.DK.05 |
| Crystal system | Triclinic |
| Crystal class | Pinacoidal (1) (same H-M symbol) |
| Space group | P1 |
| Unit cell | a = 7.536 Å, b = 11.734 Å c = 6.748 Å; α=91.70° β=93.86°, γ=104.53°; Z = 2 |
| Identification | |
| Color | Colorless, pale grey-green |
| Crystal habit | Prismatic crystals |
| Cleavage | Perfect on {001} and {1-10} |
| Tenacity | Brittle |
| Mohs scale hardness | 6 |
| Luster | Vitreous |
| Diaphaneity | Transparent |
| Density | 3.24 g/cm3 |
| Optical properties | biaxial positive |
| Refractive index | nα= 1.686 nβ= 1.694 nγ= 1.709 |
| Birefringence | δ=0.023 |
| Pleochroism | Strong with colors pink(γ') to green(α') |
| Dispersion | r > v strong |
| References | |
Scandiobabingtonite was first discovered in the Montecatini granite quarry near Baveno, Italy in a pegmatite cavity. Though found in pegmatites, the crystals of scandiobabingtonite are sub-millimeter sized, and are tabular shaped. Scandiobabingtonite was the sixth naturally occurring mineral discovered with the rare earth element scandium, and grows around babingtonite, with which it is isostructural, hence the namesake. It is also referred to as scandian babingtonite. The ideal chemical formula for scandiobabingtonite is Ca2(Fe2+,Mn)ScSi5O14(OH).
Scandiobabingtonite is found in association with orthoclase, quartz, light blue albite, stilbite, fluorite, and mica. When found with these minerals, the scandiobabingtonite crystals are emplanted on the surface of the other minerals. It also occurs as growth around green-black prismatic crystals of babingtonite. The samples of scandiobabingtonite that have been discovered have shown that they start out growing from a seed of babingtonite crystal. This is how scandiobabingtonite gets its chemical structure. The starting seed of babingtonite is still present in the center of the resulting crystal and can be detected with optical and chemical studies. Scandiobabingtonite is a uniquely rare mineral, as it occurs in very small amounts in few locations around the world. It is one of thirteen naturally occurring minerals where scandium is a dominant member. The other scandium minerals are bazzite, cascandite, hetftetjernite, jervisite, juonniite, kolbeckite, kristiansenite, magbasite, oftedalite, pretulite, thortveitite, and titanowodginite. Scandium can also concentrate in other minerals, such as in ferromagnesian minerals, aluminum phosphate minerals, meteoric minerals, and other minerals containing rare earth elements, but it occurs in trace amounts.
...
Wikipedia