He is a research scientist at the Carnegie Institution of Washington's Geophysical Laboratory and Clarence Robinson Professor of Earth Science at George Mason University, in the United States.

Hazen later recalled "He gave me a starter collection of 100 specimens, mineral field guides, and mimeographed directions to Paterson and Franklin, New Jersey.

With Wones as advisor, he completed a masters thesis on cation substitution in trioctahedral micas; his publication in American Mineralogist was his first to be highly cited.

[8][10][6] While a NATO Postdoctoral Fellow at Cambridge University in England, Hazen worked with Charles Prewitt to determine empirical relations for the effect of temperature and pressure on interatomic distances in oxides and silicates.

[1] After a brief stint measuring optical properties of lunar minerals with Peter Bell and David Mao, he started to do X-ray crystallography with Larry Finger.

Although the field had pioneering contributions from the Nobel Prize winner Percy Bridgman and a student of his, Francis Birch, in the early- to mid-20th century, it did not have a name until the 1960s, and in the 1970s some scientists were concerned that a more interdisciplinary approach was needed to understand the relationship between interatomic forces and mineral properties.

Hazen and Prewitt co-convened the first mineral physics conference; it was held on October 17–19, 1977 at the Airlie House in Warrenton, Virginia.

[13] Cooled to very low temperatures, some materials experience a sudden transition where electrical resistance drops to zero and any magnetic fields are expelled.

[15] A group led by Paul Chu at the University of Houston explored some materials made of yttrium, barium, copper and oxygen (YCBO) and were the first to obtain a critical temperature above the boiling point of liquid nitrogen.

[16] Mao and Hazen determined that the crystal structure of the superconducting phase was like that of perovskite, an important mineral in Earth's mantle.

[19] This opportunity came when a colleague at George Mason University, Harold Morowitz, realized that the temperature and pressure at a hydrothermal vent might change the properties of water, allowing chemical reactions that ordinarily require the help of an enzyme.

[20] The publication of their results, which seemed to support the deep sea vent hypothesis,[21] met with heavy criticism, especially from Stanley Miller and colleagues who believe that life emerged on the surface.

Along with the general criticism that organic compounds would not survive long in hot, high pressure conditions, they pointed out several flaws in the experiment.

[25] With Tim Filley, an expert at organic chemical analysis, and Glenn Goodfriend, a geochemist, Hazen cleaned large calcite crystals and dipped them into aspartic acid.

Hazen could not recall a mineralogist ever having asked whether a given mineral existed in a given era,[27][28] and it occurred to him that no one had ever explored how Earth's mineralogy changed over time.

[29] Based on a review of the literature, Hazen and his co-authors estimated that the number of minerals in the Solar System has grown from about a dozen at the time of its formation to over 4300 at present.

They predicted that there was a systematic increase in the number of mineral species over time, and identified three main eras of change: the formation of the Solar System and planets; the reworking of crust and mantle and the onset of plate tectonics; and the appearance of life.

[37] As the Clarence B. Robinson Professor at George Mason University, Hazen developed innovative courses to promote scientific literacy in both scientists and non-scientists.

[39] About 200 readers responded, generally supporting the idea of such a list while vehemently criticizing many of the particulars, including an informal style and sometimes vague language.

[51] For the book The Music Men, he and his wife Margaret received the Deems Taylor Award from the American Society of Composers, Authors and Publishers in 1989.

A selection of articles follows: Hazen's wife, Margee (née Margaret Joan Hindle), is a science writer and published historian.