axinite

{{Infobox mineral

|boxbgcolor=#756050| name = Axinite

| category = Cyclosilicates

| boxwidth =

| boxtextcolor= #FFFFFF

| image = Axinite-Mn - Canta, Lima, Peru.jpg

| caption = Manganaxinite

| formula = {{chem2|(Ca,Fe,Mn)3Al2BO3Si4O12OH}} or {{chem2|Ca2(Fe,Mn)Al2BSi4O15(OH)}}

|IMAsymbol=Ax{{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}}

| strunz = 9.BD.20

| system = Triclinic

| class = Pinacoidal ({{overline|1}})
(same H-M symbol)

| symmetry = P{{overline|1}}

| color = Reddish brown to yellow to colorless. Blue, violet, grey.

| habit = Tabular, wedge shaped crystals

| cleavage = Good on {100}

| fracture = Conchoidal

| mohs = 6.0–7.5

| luster = Vitreous

| refractive = n_α = 1.672–1.693
n_β = 1.677–1.701
n_γ = 1.681–1.704

| opticalprop = Biaxial (−)

| birefringence = δ = 0.011

| pleochroism = Strong

| streak = White

| gravity = 3.18–3.37

| melt =

| fusibility =

| solubility =

| other =

| references = [http://mineral.galleries.com/Minerals/Silicate/AXINITE/AXINITE.htm Axinite] {{webarchive |url=https://web.archive.org/web/20081119075930/http://mineral.galleries.com/Minerals/Silicate/AXINITE/AXINITE.htm |date=November 19, 2008 }}. Mineral Galleries[http://www.mindat.org/min-440.html Axinite]. Mindat

}}

Axinite is a brown to violet-brown, or reddish-brown bladed group of minerals composed of calcium aluminium boro-silicate, {{chem2|(Ca,Fe,Mn)3Al2BO3Si4O12OH}}. Axinite is pyroelectric and piezoelectric.

The axinite group includes:

• Axinite-(Fe) or ferroaxinite, Ca₂Fe²⁺Al₂BOSi₄O₁₅(OH) iron rich, clove-brown, brown, plum-blue, pearl-gray[http://rruff.info/doclib/hom/ferroaxinite.pdf Handbook of Mineralogy: Ferroaxinite]
• Axinite-(Mg) or magnesioaxinite, Ca₂MgAl₂BOSi₄O₁₅(OH) magnesium rich, pale blue to pale violet; light brown to light pink[http://rruff.info/doclib/hom/magnesioaxinite.pdf Handbook of Mineralogy: Magnesioaxinite]
• Axinite-(Mn) or manganaxinite, Ca₂Mn²⁺Al₂BOSi₄O₁₅(OH) manganese rich, honey-yellow, clove-brown, brown to blue[http://rruff.info/doclib/hom/manganaxinite.pdf Handbook of Mineralogy: Manganaxinite]
• Tinzenite (CaFe²⁺Mn²⁺)₃Al₂BOSi₄O₁₅(OH) iron – manganese intermediate, yellow, brownish yellow-green[http://rruff.info/doclib/hom/tinzenite.pdf Handbook of Mineralogy: Tinzenite]

Axinite is sometimes used as a gemstone.Tables of Gemstone Identification

By Roger Dedeyne, Ivo Quintens p.147