Suessite
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| Suessite | |
|---|---|
 | |
| General | |
| Category | Iron silicide |
| Formula | Fe3Si |
| IMA symbol | Sss[1] |
| Strunz classification | 1.BB.05 |
| Crystal system | Cubic |
| Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m) |
| Space group | Im3m |
| Unit cell | a = 2.841 Å; Z = 0.5 |
| Identification | |
| Color | Cream white in reflected light, Terrestrial is light gray with a yellow tint |
| Crystal habit | forms oval accumulations, polycrystalline aggregates |
| Cleavage | None |
| Specific gravity | 6.34 |
| Optical properties | X-ray Wavelength = 1.541838 |
| Other characteristics | Ferromagnetic,
degree of disorder = 11%, Curie point = 550°C, magnetic moment = 4.6 μB, microhardness = 531–532 kg/mm2 |
| References | [2][3][4][5] |
Suessite is a rare iron silicide mineral with chemical formula: Fe3Si.[6] The mineral was named after Professor Hans E. Suess. It was discovered in 1982 during the chemical analysis of The North Haig olivine pigeonite achondrite (ureilite). It is a cream white color in reflected light, and ranges in size from 1 μm "blebs" to elongated grains that can reach up to 0.45 cm in length.[7] This mineral belongs in the isometric crystal class. The isometric class has crystallographic axes that are all the same length and each of the three axes perpendicular to the other two. It is isotropic, has a structural type of DO3 and a crystal lattice of BiF3.[8]
Suessite is an isotropic mineral, Isotropism is defined as an optical property of a mineral that stays the same from whatever direction it is observed. In thin-section microscopy, an isotropic mineral has only one refractive index. This means that light that passes through the mineral is not split into two different directions, but it passes through unchanged.[9] Suessite, as determined from the previous definition, only has one index of refraction. When Keil, Fuchs, and Berkley first discovered the mineral they described it as having a relatively low optical relief, but there was no determination of the index of refraction.[10] In plane polarized light, suessite is a reddish-brown color that shows no pleochroism.[11]