Calderite

{{Short description|Mineral in the garnet group}}

{{infobox mineral

| name = Calderite

| category = Silicate mineral

| image = Calderite garnet.jpg

| imagesize = 260px

| alt = Dark red hexoctahedral crystals on light colored rock

| caption = Calderite crystals on matrix from Sunndal Municipality Norway

| formula = (Mn²⁺Ca)₃(Fe³⁺Al)₂(SiO₄)₃

| IMAsymbol=Cdr{{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 = 9.AD.25 (10 ed)
8/A.08–40 (8 ed)

| dana = 51.4.3a.6

| system = Cubic

| class = Hexoctahedral (m{{overline|3}}m)
H-M symbol: (4/m {{overline|3}} 2/m)

| symmetry = Ia{{overline|3}}d

| unit cell = a = 11.819 Å; Z = 8

| color = brownish red to brownish yellow

| twinning =

| cleavage = None

| fracture =

| tenacity =

| mohs = 6.5–7.5

| luster = Vitreous

| streak = white

| diaphaneity = transparent to translucent

| gravity = 3.756

| density =

| opticalprop = Isotropic

| refractive = n = 1.872

| birefringence =

| pleochroism =

| 2V =

| dispersion =

| extinction =

| length fast/slow =

| fluorescence =

| absorption =

| melt =

| fusibility =

| diagnostic =

| solubility =

| other =

| references = [http://www.mindat.org/min-864.html Mindat.org][http://webmineral.com/data/Calderite.shtml Webmineral.com]

}}

Calderite is a mineral in the garnet group with the chemical formula (Mn²⁺, Ca)₃(Fe³⁺, Al)₂(SiO₄)₃.

It is dark reddish brown to dark yellowish in color and generally granular massive in form.[http://rruff.geo.arizona.edu/doclib/hom/calderite.pdf Handbook of Mineralogy]

It was named for geologist James Calder who worked on the geology of India. The name was first applied to a rock in manganese deposits in Katkamsandi, Hazaribagh district, Bihar and at Netra, Balaghat district, Madhya Pradesh, India.

later transferred to its predominant mineral. In 1909 it was described as a mineral from Otjosondu, Otjozondjupa Region, Namibia.