sinoite

{{Infobox mineral

| name = Sinoite

| category = Silicate mineral

| boxwidth =

| boxbgcolor =

| image = Sinoite.png

| caption = Crystal structure of sinoite. Atoms: red – O, blue – N, gray – Si.

| formula = Si₂N₂O

| IMAsymbol = Sno{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| molweight =

| strunz = 1.DB.10

| dana = 1.3.9.1

| system = Orthorhombic

| class = Pyramidal (mm2)
H-M symbol: (mm2)

| symmetry = Cmc2₁

| unit cell = a = 8.84 Å, b = 5.47 Å
c = 4.83 Å, Z = 4

| color = From colorless to light gray

| twinning =

| cleavage = None

| fracture =

| tenacity =

| mohs =

| luster = Vitreous

| refractive = n_α = 1.740
n_β = 1.855
n_γ = 1.855

| opticalprop = Biaxial (-)

| birefringence = δ = 0.115

| pleochroism =

| streak = White

| gravity = 2.83

| diaphaneity = Transparent to translucent

| references = [http://rruff.geo.arizona.edu/doclib/hom/sinoite.pdf Sinoite]. Handbook of Mineralogy[http://www.mindat.org/min-3676.html Sinoite]. Mindat.org[http://webmineral.com/data/Sinoite.shtml Sinoite]. Webmineral

}}

Sinoite is a rare mineral with the chemical formula Si₂N₂O. It was first found in 1905 in chondrite meteorites and identified as a distinct mineral in 1965. Sinoite crystallizes upon meteorite impact as grains smaller than 0.2 mm surrounded by Fe-Ni alloys and the mineral enstatite. It is named after its SiNO composition and can be prepared in the laboratory as a silicon oxynitride ceramic.

The crystalline structure of silicon oxynitride is built by SiN₃O tetrahedra connected through oxygen atoms along the c axis and through nitrogen atoms perpendicular to it. The strong covalent bonding of this structure results in high flexural strength and resistance to heating and oxidation up to temperatures of about 1600 °C.

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