Namesake Minerals #2

This week it’s all about namesake minerals that are out of this world! That’s because I decided to dedicate this post to minerals that were named after astronauts. Also, one of these minerals was first discovered on the Moon.


Armalcolite (black crystals), from Smoky Butte, Garfield Country, Montana, USA (image by Tony Peterson, from

Quick facts:

  • Oxide mineral
  • Found in titanium-rich basalts and microbreccia. Associated with iron-titanium oxides
  • Type locality: Tranquillity Base (Apollo 11 landing site), Mare Tranquillitatis, the Moon
  • Formula: (Mg,Fe2+)Ti2O5
  • Crystal system: Orthorhombic
  • Hardness: 5
  • Density: 4.94 g/cm3

Armalcolite derives its name from Neil Armstrong, Buzz Aldrin and Michael Collins. It was named in 1970 to honour the first astronauts to visit the Moon during the Apollo 11 mission (16th – 24th July 1969). During the mission, 21.5kg of lunar samples were collected from Mare Tranquillitatis which is an iron-rich basaltic plain. Other minerals discovered in this location were tranquillityite and pyroxferroite.


Left: From left to right, Armstrong, Collins and Aldrin (image by NASA, from Right: The landing site of Apollo 11 (image by Soerfm, from

A few years later, armalcolite was found on Earth. It commonly occurs as 300µm long grains in ultramafic rocks, lamproites, kimberlites and impact craters (e.g. the Ries Crater in Bavaria, Germany). Grains several millimetres in size can only be produced artificially in a laboratory. Fortunately, a trip to the Moon isn’t the only way to obtain armalcolite of a lunar origin; in 2003, lunar meteorites containing this mineral were found in Oman.

thin sections

Left: Thin section of lunar sample 70017, image width = 8mm (image by Kurt Hollocher, from Right: Thin section of lamproite from Smoky Butte, Garfield County, Montana, USA (image by Tony Peterson, from

Sample 70017 is a vesicular basalt from the 1972 Apollo 17 mission to Mare Imbrium. The thin section of this sample shows opaque armalcolite with colourless plagioclase and pyroxene which has a fractured appearance. The second thin section shows opaque armalcolite in lamproite with pyroxene, apatite (small, high relief grains) and leucite (cloudy grains).


armstrongite 2

Armstrongite, from Khan Bogdin Massif, Gobi Desert, Mongolia (image by Leon Hupperichs, from

Quick facts:

  • Silicate mineral
  • Associated with alkali rocks
  • Type locality: Dorozhnyi pegmatite, Khan Bogdin Massif, Gobi Desert, Mongolia
  • Formula: CaZrSi6O15•3(H2O)
  • Crystal system: Monoclinic
  • Hardness: 4.5
  • Density: 2.562 – 2.593 g/cm3

Armstrongnite is the second mineral named after Neil Armstrong (lucky guy!) but its origin is terrestrial. It was named on the 10th annversary of the Apollo 11 Moon landing. The Khan Bogdin Massif consists of arfvedsonite-aegirine granite with pegmatites containing rare earth element (REE) concentrations of up to 3-4.5%.



Gagarinite-(Ce), from Strange Lake, Quebec, Canada (image by John Veevaert, from

Quick facts:

  • Halide mineral (radioactive)
  • Usually found as grains in pegmatites
  • Type locality: Strange Lake, Quebec, Canada
  • Formula: Na(REExCa1-x)(REEyCa1-y)F6; REE represents elements such as lanthanum, cerium, etc.
  • Crystal system: Trigonal
  • Hardness: 3.5
  • Density: 4.44 – 4.55 g/cm3

Yuri Gagarin (image from

The original name for gagarinite was zajacite as it was initially named after Dr. Ihor Stephan Zajac who led the expedition responsible for discovering the mineral at Strange Lake in 1993. In 2010, the mineral was renamed by the International Mineralogical Association after Yuri Gagarin. Gagarin was a Russian astronaut and the first human to journey into outer space and orbit the Earth on 12th April 1961.





Dergunov A. B. 2001. Tectonics, Magmatism, and Metallogeny of Mongolia. Psychology Press


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