Mineral Physics Quest to the Earth's Core

Because of its remoteness, together with pressures from 140 to 360 gigapascals and temperatures from 4000 to 7000 K, most direct observations of the Earth's core properties have come from teleseismic studies, requiring large earthquake sources and well‐positioned seismometers to detect weak wave signals that have traversed the Earth's deepest interior. The decoding of geochemical signatures of the core—potentially carried to the surface in plumes originating at the core‐mantle boundary—faces numerous challenges of the debated integrity of this hypothesis. For these reasons, understanding the Earth's core requires multidisciplinary efforts. In the past two decades, deep‐Earth scientists have unveiled a number of unusual and enigmatic phenomena of the core, including inner core anisotropy, differential rotation of the inner core, fine‐scale seismic heterogeneity, and the possible existence of the prefer‐oriented hexagonal close packed (hcp, in which two closely packed layers stack alternately along a crystallographic axis) and/or body‐centered cubic (bcc, in which eight atoms reside at the corners and one atom resides at the center of the cubic cell) iron/nickel/light element alloys in the inner core (Figure 1). In this feature article, we summarize recent new findings and frontiers about the nature of the core from mineral physics research.