Zagamiite

CaAl2Si3.5O11
IMA status
  • Approved
IMA symbol
Zag
IMA approved
2016
Also known as
  • IMA2015-022a
  • Zagamiiet

Where it forms, where it's found

Geological setting

Shock melt pockets in basaltic shergottites

Type locality
Zagami Martian meteorite
  1. Faskari
  2. Katsina
  3. Nigeria

11.7333°, 7.0833°

2recorded occurrences
Source · OpenStreetMap

Physical

Transparency
Transparent
Colour
colorless
Density
3.79 g/cm³

Crystallography

Crystal system
Hexagonal
Space group
P63/mmc
Cell parameters
a = 5.403(2) Å · c = 12.77(3) Å
Z
2
Type-locality form

fine-grained prismatic crystals, less than 50 nm × 100 nm to 400 nm × 1 μm in size, within shock melt pockets

Chemical composition

Constituent elements
Mass composition breakdown
ElementAtoms At. mass g/mol Mass g/molMass share
8OOxygenOxygen1115.999175.989
47.78%
14SiSiliconSilicon3.528.08598.297
26.69%
13AlAluminiumAluminium226.98253.964
14.65%
20CaCalciumCalcium140.07840.078
10.88%
Total368.328100.00%

Mass share = atoms × atomic mass ÷ molar mass × 100

From IMA formula

Synonyms

  • IMA2015-022a
  • Zagamiiet

In other languages

German
IMA 2015-022a · Zagamiit

Classification

Strunz
10th ed.

9.HA.47

  • 9SilicatesClass
  • 9.HUnclassified silicatesDivision
  • 9.HAWith Alkali and Alkali-earth ElementsGroup
  • 9.HA.47ZagamiiteSpecies

Literature, links & citation

Citations
  1. 2017Ma, C., Tschauner, O. & Beckett, J.R. (2017) A new high-pressure calcium aluminosilicate (CaAl2Si3.5O11) in martian meteorites: another after-life for plagioclase and connections to the CAS phase. Lunar and Planetary Science XLVIII, 1128.pdf. [https://www.hou.usra.edu/meetings/lpsc2017/pdf/1128.pdf]
  2. 2017Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2017) New minerals and nomenclature modifications approved in 2017. CNMNC Newsletter No 36. Mineralogical Magazine, 81 (2) 403-409 doi:10.1180/minmag.2017.081.022DOI: 10.1180/minmag.2017.081.022
  3. 2019Ma, C., Tschauner, O., Beckett, J.R. (2019) A Closer Look at Martian Meteorites: Discovery of the New Mineral Zagamiite, CaAl2Si3.5O11, a Shock-Metamorphic, High-Pressure, Calcium Aluminosilicate. Ninth International Conference on Mars, 22-25 July, 2019, Pasadena, California. LPI Contribution No. 2089.
  4. 2021(2021) Zagamiite. Handbook of Mineralogy. Mineralogical Society of America
  5. 2024Ma, Chi, Tschauner, Oliver, Beckett, John R., Greenberg, Eran, Prakapenka, Vitali B. (2024) Zagamiite, CaAl2Si3.5O11, the Hexagonal High-Pressure CAS Phase with Dominant Si, as a Mineral from Mars. Minerals, 14 (1) doi:10.3390/min14010018DOI: 10.3390/min14010018
Cite this entry
@misc{mineral2026,
  author    = {Mineral Index editorial board},
  title     = {Zagamiite — Mineral Index},
  year      = {2026},
  url       = {https://mineralindex.org/minerals/zagamiite-51594},
  note      = {Accessed 2026-05-11}
}