All of these oxides are described by NASA as occuring with trace
This is titanium oxide of composition TiO2, and is usually found
associated with ilmenite. Most commonly, it is due to the reduction of
ilmenite and/or armalcolite.
In this association, it often contains Nd, Cr, Ta, and lanthanide
Colour is typically reddish-brown, but it may be black, violet, yellow
or green. Typically yellow-red/brown in thin section. Density is
4.2-5.5 g/cm3. Rutile is insoluble in acids, but is decomposed by
alkali carbonate fusion.
Synthetic rutile has a dispersion much higher than diamond (B-G ~ 0.3)
and is used as a germstone.
This is of the formula ZrO4 and is thought to be due to meteoritic
contamination which has been incorporated into the original melts.
Also known as zirconolite, this has the formula CuZrTi2O7.
This has the formula Al2O3. This might be a contamination
may not be indigenous to the Moon.
Density is 4 g/cm3, and it is insoluble in all acids. It is notably
hard (9), resulting in abnormally high relief in thin section.
This is of the formula Fe2O3 - a common Fe ore on the Earth.
This might be a contamination product, and not be indigenous to the
Terrestrially, hematite is rare in igneous rocks, but common in
metamorphic and sedimentary rocks. It is the most common cause of red
colouration in sedimentary rocks.
This is of the formula Fe3O4, and is classified as a spinel due
to its crystal structure. Density is 5.2 g/cm3.
Magnetite is black, and is often soluble in HCl.
See the section on spinels for further information.
This is formula FeO(OH), and as such is not strictly an oxide. The NASA
Handbook of Lunar Materials lists this as a possible contamination
product, but the Lunar Sourcebook goes into more detail.
Goethite has been found in rocks from every Apollo mission, and is
often described as "rust". It has been shown that akaganeite
(beta-FeOOH) is due to terrestrial water vapour contamination, causing
the oxidation of lawrencite (FeCl2) [Taylor et al 1973]. Hence there
is still no evidence for indigenous water on the Moon.
Terrestrially, goethite occurs primarily as a weathering product.
Density is approxiumate 4.3 g/cm3. Colours vary from yellow through
orange to red. Soluble in HCl, and dehydrates to alpha-Fe2O3.
Taylor LA, Mao HK, Bell PM (1973) "Rust" in the Apollo 16 Rocks. Proc.
Lunar Sci. conf. 4th, pp 829-839.
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