Suessite

suessite

troilite

kamacite

pigeonite

Images

Formula: Fe₃Si
Silicide of iron
Crystal System: Isometric
Specific gravity: 7.08 calculated
Colour: Steel-grey
Magnetism: Strongly ferromagnetic
Common impurities: Fe may be replaced by minor Ni
Environments

Plutonic igneous environments
Meteorites

Suessite is an uncommon accessory in some iron meteorites (Mindat).

Localities

Asuka meteorites, Sør Rondane Mountains, Queen Maud Land, Eastern Antarctica, Antarctica.
The carbonaceous CH3 chondrite Asuka 881020 contains suessite, naquite and perryite, in addition to barringerite, andreyivanovite, troilite, daubréelite, pyrrhotite, pentlandite and magnetite. There are places that are free of silicon and others where silicon is enriched. Planetoid 21 Lutetia is proposed for the source of the meteorite (Minerals 2022.12.188. https://doi.org/10.3390/min12020188)

In the Elephant Moraine meteorites, Elephant Moraine, Victoria Land, Eastern Antarctica, Antarctica, the EET 83309 meteorite is a ureilite consisting of olivine, pyroxene and plagioclase in one grain (0.6 mm in size), as well as suessite and many fragments (greater than 300 µm in size) of opal, which, as a 10 µm thick skin, completely envelopes the grains. In the EET 87720 meteorite the (unconfirmed) detection of a hapkeite grain has been reported (Minerals 2022.12.188. https://doi.org/10.3390/min12020188)

At the Frontier Mountain meteorite trap, Victoria Land, Eastern Antarctica, meteorites have been found that contain Fe_xSi_y. In all of them, the unnamed phase (Fe,Ni)₉Si was identified. FRO 90168 and FRO 93008 contain suessite in the veins, produced by high degrees of shock (as mosaic olivine). A grain of Fe₂Si, probably hapkeite, was detected in FRO 90228 ureilite. Remarkably, (Fe,Ni)₃Si and hapkeite were discovered in the veins of ureilites, indicating their origin as impact-induced melt (Minerals 2022.12.188. https://doi.org/10.3390/min12020188).

At the type Locality North Haig meteorite, Sleeper Camp, Haig, Kalgoorlie-Boulder Shire, Western Australia, suessite generally occurs as anhedral vein fillings in interstitial cracks and fissures between silicate grains. Suessite ranges in grain size from 1 micron blebs to linear vein fillings occasionally up to several hundred microns in length. Other opaques in North Haig are rare troilite which occurs in blebs about 1 to 50 microns across, both interstitially to and within silicate grains, as well as extremely rare 1 to 2 micron blebs of low-Ni kamacite that occur exclusively within silicate grains, not in the interstitial carbonaceous matrix. Suessite was not observed in direct contact with either troilite or kamacite. North Haig is a meteorite that has been subjected to considerable terrestrial weathering. Since metallic phases tend to most readily weather to hydrous ferric oxide, it is difficult to estimate the pre-terrestrial abundance of suessite and kamacite. However, suessite, which is strongly ferromagnetic, is by far the most abundant metallic phase, whereas kamacite is extremelv rare. Minerals associated with suessite include olivine, pigeonite, kamacite and troilite, as well as carbonaceous material (HOM).
Suessite from the North Haig meteorite - Image

At Dar al Gani, Jufra District, Libya, suessite is found in meteorites DaG 1000, heavily shocked DaG 1023 and DaG 999.
In the ureilite DaG 319, suessite and perryite have been identified.
The highly shocked ureilite DaG 1047 has feldspars, olivine, pyroxenes and troilite, and also suessite and kamacite.
The ureilite DaG 1054 is highly shocked. It consists mainly of olivine, a few orthopyroxenes, rare grains of sulphide (mainly troilite), carbon including tiny diamonds at the grain boundaries, and suessite, with fractions of Cr and Ni, grains or metal veins.
Suessite, hapkeite and naquite are present in the barely weathered meteorite, DAG 1066. The meteorite shows signs of being highly shocked. The iron silicides indicate a formation under significantly reducing conditions. They are embedded as minute spots in a matrix largely consisting of olivine crystals (0.2 to 1.5 mm in size) and, to a lesser extent, pyroxene and feldspar, on the edge of the olivine grains and graphite. Other inclusions are pentlandite and FeNi. The embeddings are partially ureilitic, carbonaceous chondrites, or chondrules (chondrules form as molten or partially molten droplets in space before being accreted to their parent asteroids - Wiki) rich in forsterite and enstatite. The meteorite is assumed to be of ureilite origin (Minerals 2022.12.188. https://doi.org/10.3390/min12020188)

North Western Africa
The ureilite NWA 1241 consists of silicates (olivine, pigeonite), carbonaceous material, nanodiamonds, and, as the main abundant metallic phase, suessite. It is assumed that due to an impact on the ureilite parent body, suessite was produced by olivine and kamacite at about 1130 to 1230^oC and very high fugacity of oxygen (Minerals 2022.12.188. https://doi.org/10.3390/min12020188).

At Sayh al Uhaymir meteorites, Al Wusta Governorate, Oman, the carbonaceous CH3 chondrite SaU 290 contains suessite, naquite and perryite, in addition to barringerite, andreyivanovite, troilite, daubréelite, pyrrhotite, pentlandite and magnetite. There are places that are free of silicon and others where silicon is enriched. Planetoid 21 Lutetia is proposed as the source of the CH3 meteorite (Minerals 2022.12.188. https://doi.org/10.3390/min12020188).

At Shunga, Zaonezhie peninsula, Medvezhyegorsky District, Republic of Karelia, Russia, crystalline and microcrystalline inclusions of suessite have been reported in veins of the mineraloid shungite (elementary noncrystalline carbon), as well as in shungite basalts near Lebeshchina, Karelia, Russia. These are very similar to meteoritic suessite, (Minerals 2022.12.188. https://doi.org/10.3390/min12020188)

Khatyrka meteorite, Iomrautvaam massif, Anadyrsky District, Chukotka Autonomous Okrug, Russia.
Iron silicides occur in grain 126 of the carbonaceous chondrite Khatyrka CV3. The meteorite is believed to be one of the solar system's building blocks, created some 4.5 billion years ago. It is rich in Al, Ni, and Cu, and the iron silicides naquite and suessite have been found. There are many other minerals in that meteorite, such as hercynite, chromite, magnetite, corundum, iron, taenite, hollisterite, kryachkoite, stolperite and steinhardtite; it is an unusual mix. Moreover, icosahedrite, as well as decagonite, the first natural quasicrystals, were detected. It was assumed that these were formed by shock synthesis when planetoids collided. Khatyrka experienced at least one high-velocity impact event (Minerals 2022.12.188. https://doi.org/10.3390/min12020188).

Tim-Yastrebovskaya structure, Voronezh Oblast, Russia.
A natural terrestrial origin is assumed for the suessite in the magmatic norite breccias of the Tim-Yastrebovskaya structure, which were unearthed from a depth of 320 to 446 m. The suessite is found together with native gold, chromium, iron and bismuth, with alloys of gold-cadmium and natural zinc-copper, graphite, chromium nitride as micro-inclusions in native chromium, tungsten carbide and moissanite (Minerals 2022.12.188. https://doi.org/10.3390/min12020188).

At the Blackville site, Barnwell County, South Carolina, USA, suessite was found in molten siliceous glass situated in layers at a depth of 1.75 to 1.9 m. Glassy spherules (15 to 1940 µm in size) were also present. The suessite appeared together with globules of native iron, quenched grains of corundum and mullite and Fe₃C spherules. The glass also contains the mineraloid lechatelierite. The presence of mullite, suessite and lechatelierite in particular, testifies to high temperatures and pressures. suessite forms at 2000 to 2300^oC. Lechatelierite in granite requires a pressure of 85 Gpa (839 thousand times atmospheric pressure) to form. Thus, it is suggested that the material formed during an impact that melted the silicates (Minerals 2022.12.188. https://doi.org/10.3390/min12020188).

At the Chinarsay prospect, Khandiza VMS deposit, Surxondaryo, Uzbekistan, suessite was discovered in the ore-bearing perlite rhyolite deposits of the submarine volcano. It is thought that the outflow of acidic lava from the volcano produced a reducing environment. A rapid decrease in temperature and pressure led to the formation of suessite, together with manganese-wüstite and spherular Fe₃C (Minerals 2022.12.188. https://doi.org/10.3390/min12020188).

At the Ir-Tash Stream Basin, Arashan Mtn, Chatkal-Kuraminskii Range, Tashkent, Uzbekistan, amygdules of basaltic porphyry covered with thin graphite rims have been found, containing calcite, khamrabaevite, suessite and gupeiite. The suessite accumulates in masses 0.25 mm up to 4 cm across. Within the suessite there are graphite and cubic crystals of TiC, preferentially at the rims, and tiny inclusions of feldspar, lepidocrocite, quartz, and octahedral mica (Minerals 2022.12.188. https://doi.org/10.3390/min12020188)

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