A Journey to the Center of the Earth

The Hebrew University's crucial mission is to attract and support the next generation of brilliant scientists and intellectuals. Our success in recruiting new faculty members depends on the ability to provide these young scholars with competitive research and teaching conditions.

Dr. Yaakov Weiss joined the faculty of the Hebrew University’s Fredy and Nadine Herrmann Institute of Earth Sciences in September 2018. This follows three years as an associate research scientist at the Lamont-Doherty Earth Observatory of Columbia University and three years as a Lamont postdoctoral fellow. Weiss received his PhD, MSc and BSc in geology from the Hebrew University. In parallel to working on his doctorate from 2007–12, Weiss worked as the manager of the University’s Electron Probe Laboratory as well as being the Curator of the Geological Collection of Israel’s National Natural History Collections.

Weiss’s scientific interests focuses three areas. One, on trapped minerals and fluids in diamonds as “time capsule” samples of the Earth’s deep mantle and monitors of deep mantle processes. Two, cycles of volatiles and incompatible elements between different mantles (and crystal) reservoirs. And, three, the application of phenocryst compositions in basaltic magmas as proxies for the lithologies contributing to mantle melts. Weiss has published in some of the leading academic science and geology journals including a 2015 cover article in Nature.

The Research: Diamond Dealing and Time Capsules

Dr. Yaakov Weiss deals with diamonds. His expertise however is not in jewelry store diamonds, rather the inferior, more dirty-looking diamonds used for industry. These lower-grade stones contain so-called inclusions – chemical intruders in the crystal. Inclusions contain worlds of information - about the deep, inaccessible regions of the earth where diamonds come from, how diamonds are formed and other deep earth processes. A diamond is a time capsule that captures a moment in time in the Earths’ history.

In a recent project, Weiss studied diamonds from Canada’s Northwest Territories. Working with colleagues, he investigated fibrous diamonds – a rapid form of diamond growth. Analysis of diamond-forming fluid inclusions in these diamonds showed them to be rich in carbon and a highly saline solution – with plenty of chlorine, potassium and sodium – similar to seawater. Other researchers have shown that plate tectonics in the Northwest Territories have included complex evolutions of repeated opening and closing of ocean basins. This research enabled Weiss and his colleagues to connect the dots as they showed that ancient seawater was involved in the formation of diamonds in the deep mantle. This understanding links diamond formation with global plate tectonics and recycling of surface material back into the earths’ mantle.

“The position at the Hebrew University was a great opportunity, which overcame some strong arguments on staying in the United States.  I am happy to be part of the Hebrew University, it is a great institute and I hope we will establish a happy life back in Israel.”

In another study, Weiss investigated tiny droplets of fluid encapsulated within African gem-grade diamonds. Such droplets are common in inferior-grade diamonds like the fibrous ones but not often found in gems. Many scientists contend that inferior-grade diamonds and gemstones each crystallize out of two different types of fluids. Weiss tested this and found that the gem’s fluids are closer in composition to those in the lower-grade diamonds, implying the formation of these two diamond types from similar diamond-forming fluids.

Weiss’ research has practical implications for diamond dealers who do specialize in jewelry. Greater knowledge of trace elements in diamond inclusion could lead to chemical “fingerprints” which would tell where gem-grade diamonds originated. This would enable better enforcement of the Kimberly Process, a 2003 UN agreement blacklisting “blood diamonds” – gems from nations where mining is controlled by warlords or corrupt governments. 

“The position at the Hebrew University was a great opportunity, which overcame some strong arguments on staying in the United States.  I am happy to be part of the Hebrew University, it is a great institute and I hope we will establish a happy life back in Israel.”

- Dr. Yaakov Weiss