What is Titanite?
{{Infobox mineral|name=Titanite (Sphene)|category=[[Silicate minerals|nesosilicate]]|boxwidth=|image=Titanite crystals on Amphibole - Ochtendung, Eifel, Germany.jpg|imagesize=260px|caption=Titanite crystals on amphibole (image width 2 mm)|formula=CaTiSiO<sub>5</sub>|IMAsymbol=Ttn<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|url=https://www.cambridge.org/core/journals/mineralogical-magazine/article/imacnmnc-approved-mineral-symbols/62311F45ED37831D78603C6E6B25EE0A|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616}}</ref>|strunz=9.AG.15|system=[[Monoclinic]]|class=Prismatic (2/m) <br /><small>(same [[H-M symbol]])</small>|symmetry=''P''2<sub>1</sub>/a|unit cell=a = 7.057&nbsp;[[Ångström|Å]], b = 8.707&nbsp;Å <br />c = 6.555&nbsp;Å; β = 113.81°; Z&nbsp;=&nbsp;4|colour=Reddish brown, brown, gray, black, yellow, green, or red, colourless|habit=Flattened wedge-shaped crystals, also massive|twinning=Contact and penetration on {100}, lamellar on {221}|cleavage=Distinct on [110], parting on {221}|fracture=Sub-conchoidal|tenacity=|mohs=5 to 5.5|luster=Subadamantine tending to slightly resinous|streak=Reddish white|diaphaneity=Translucent to transparent|gravity=3.48 to 3.60|density=|polish=|opticalprop=Biaxial (+); very high [[Optical relief|relief]]|refractive=nα = 1.843 – 1.950<br>nβ = 1.870 – 2.034 <br>nγ = 1.943 – 2.110|birefringence=δ = 0.100 – 0.160|pleochroism=Strong: X = nearly colorless; Y = yellow to green; Z = red to yellow-orange|2V=17 to 40° (measured)|dispersion=r > v strong|extinction=|length fast/slow=|fluorescence=|absorption=|melt=|fusibility=|diagnostic=|solubility=|other=[[Image:Radioactive.svg|25px]] [[Radioactive]] – may be metamict|alteration=|references=<ref name=Handbook>{{cite web| url = http://rruff.geo.arizona.edu/doclib/hom/titanite.pdf| title = Handbook of Mineralogy}}</ref><ref name=Webmin>{{cite web| url = http://webmineral.com/data/Titanite.shtml| title = Webmineral