Peter Heaney

Peter Heaney

Peter Heaney studies materials not to learn how to synthesize them or improve their properties, as most materials scientists do. His materials were synthesized billions of years ago by processes within the earth's crust. Heaney is a geochemist studying minerals in exquisite detail to learn how they came to be. His current research involves characterizing carbonados - porous, polycrystalline diamonds containing 100 nm-200 mm grains. While the origin of carbonados is controversial, most geologists agree that they were not formed by the same processes that produce gem quality (kimberlitic) diamonds. To study carbonados Heaney uses transmission electron microscopy (TEM) to look for impurities and defects that offer clues as to their origins. Recent studies have revealed metallic transition metal impurities including Ni, Fe, Cu, Ti and Cr (see image, below). The presence of these species suggests meteoritic origins; these elements are nearly always present as oxides in the earth's crust. Heaney and collaborators have also employed secondary ion mass spectrometry (SIMS) to map the 13C/12C and 15N/14N ratios within single specimens. These ratios suggest organic origins different from kimberlitic diamonds. Heaney and others hypothesize that a meteorite containing the metal species that his group has observed impacted the earth ~3.5 billion years ago, generating the extreme pressures and temperatures necessary to convert organic matter on the earth's surface into diamond.

Heaney recently chaired a special symposium of the American Geophysical Union meeting on the characterization of kimberlitic diamonds. The aim was to determine methods of identifying the geographical origin of specific diamonds so that "conflict" diamonds could be distinguished from legitimate diamonds. [Conflict diamonds are violently expropriated from miners by warlords in certain African countries and subsequently sold on the black market to buy arms.] The group has the ambitious goal of finding a non-destructive, inexpensive method of characterizing diamonds. Their work is ongoing.

Not all of Heaney's work revolves around diamonds. He has current funding in environmental remediation using specially designed Mn-containing clays for heavy metal cation exchange media. With collaborators J. Post (Smithsonian) and S. Komarneni (PSU), he and his graduate student perform time resolved, in situ x-ray diffraction studies using the National Synchrotron Light Source at Brookhaven National Lab to document structural changes in clays as they are exposed to solutions rich in various heavy metals. He also has a collaborative DOE project with Susan Brantley (Geosciences) to study silica scale in geothermal energy production. Nanometer sized silica colloids in heated sub-surface water precipitate out onto piping requiring expensive maintenance. Brantley and Heaney are exploring the effects of water chemistry on the coagulation of silica colloids with a goal of preventing the buildup.

Peter Heaney received his Ph.D. from Johns Hopkins University. After post doctoral stints at the Smithsonian Institution and Cambridge he moved to Princeton. In 1998 he accepted a position in the Geosciences department at Penn State.

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