dorrite

{{Infobox mineral | name = Dorrite | boxwidth = | boxbgcolor = purple | boxtextcolor = #fff | image = Dorrite.jpg | imagesize = | alt = | caption = Reddish-brown dorrite crystals from Chelyabinsk, Russia | category = Inosilicate Sapphirine supergroup | formula = Ca2Mg2Fe43+(Al4Si2)O22 | IMAsymbol = Dor | molweight = 893.97 g/mol | strunz = 9.DH.40 | dana = 69.2.1a.2 | system = Triclinic Unknown space group | unit cell = a = 9.98, b = 5.08 c = 5.24 [Å]; β = 99.9° | color = Dark red-brown to dark brown | colour = | habit = Anhedral; Small prismatic crystals; Pseudomonoclinic | twinning = Common, producing a pseudomonoclinic symmetry | cleavage = Good cleavage assumed to be parallel to {010} and {001} | fracture = Irregular | tenacity = | mohs = 5 | luster = Submetallic | streak = Grey | diaphaneity = Subopaque | gravity = | density = 3.959 g/cm3 | polish = | opticalprop = | refractive = α=1.82β=1.84γ=1.86 | birefringence = δ = 0.040 | pleochroism = X=red-orange to brownY=yellowish brownZ=greenish brown | 2V = 90° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = Very strong | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | var1 = | var1text = | var2 = | var2text = | var3 = | var3text = | var4 = | var4text = | var5 = | var5text = | var6 = | var6text = | references = }}

Dorrite is a silicate mineral that is isostructural to the aenigmatite group. It is most chemically similar to the mineral rhönite [Ca2Mg5Ti(Al2Si4)O20], made distinct by a lack of titanium (Ti) and the presence of Fe3+. Dorrite is named for Dr. John (Jack) A. Dorr, a late professor at the University of Michigan that researched in outcrops where dorrite was found in 1982. This mineral is sub-metallic resembling colors of brownish-black, dark brown, to reddish brown.