Baddeleyite is a rare zirconium oxide mineral (ZrO2 or zirconia), occurring in a variety of monoclinic prismatic crystal forms.

It is transparent to translucent, has high indices of refraction, and ranges from colorless to yellow, green, and dark brown.

This is because, when silica is free in the system (silica-saturated/oversaturated), zircon is the dominating phase, not baddeleyite.

It has been observed in thin section that baddeleyite forms within plagioclase grains.

Associated minerals include ilmenite, zirkelite, apatite, magnetite, perovskite, fluorite, nepheline, pyrochlore and allanite.

[2] Because of their refractory nature and stability under diverse conditions, baddeleyite grains, along with zircon, are used for uranium-lead radiometric age determinations.

Teall – director of the British Geological Survey in the early 1900s – baddeleyite was discovered consequent to the discovery of geikielite.

Baddeley sent specimens of several pebbles from the Rakwana railroad excavations to the Museum of Practical Geology in London, where a Mr. Pringle examined them and attempted to classify them.

Pringle was unable to assign the specimens to a known mineral species and submitted them to Teall.

After analyzing the specimens, Teall concluded that the mineral was mainly composed of titanic acid and magnesia, with an incidental mixture of protoxide of iron.

While trying to find the specimens, Teall noticed that one of them was different from the rest: This new mineral was black in color, with a submetallic lustre, and a hardness of 6.5 .