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Where, and how, else might high pressure ice phases be found? Europa, mentioned in another answer, is not a good candidate because it is not all that icy; its ice layer is too thin to generate the needed high pressures (and we know of no processes similar to the formation of diamond-borne Ice VII on Earth). Ganymede, Callisto, Titan and Triton are the large moons with thick enough ice/water layers to make bulk high pressure ice phases a realistic possibility. [Ref. 2](https:// doi.org/10.1002/2017JE005338) explores the possibilities of using seismic measurements to identify phase structures on icy moons, for example suggesting that an Ice VI layer could be detected beneath a liquid water layer. Different ice phases would be distinguished by their higher densities and thus higher wave propagation velocities versus the ordinary stuff now (January 2019) on the ground in Chicago. Such ice/water structural analysis is motivated by the prospect of underground oceans supporting life and how the presence or absence of ocean-bottom ice phases would impact this possibility. So ... Stay tuned.

1. O. Tscauner, S. Huang, E. V. B. Prakapenka, C. Ma, G. R. Rossman, A. H. Shen, D. Zhang, M. Newville, A. Lanzirotti, K. Tait (2018). "Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle". Science 359 (6380), 1136-1139. https://www.science.org/doi/10.1126/science.aao3030.

2. S.C Stähler, M. P. Planning, S. D. Vance, R. D. Lorentz, N. van Driel, T. Nissen-Meyer, S. Kedar (2018). "Seismic propagation in icy ocean worlds". Journal of Geophysical Research: Planets, 123. https:// doi.org/10.1002/2017JE005338.

Where, and how, else might high pressure ice phases be found? Europa, mentioned in another answer, is not a good candidate because it is not all that icy; its ice layer is too thin to generate the needed high pressures (and we know of no processes similar to the formation of diamond-borne Ice VII on Earth). Ganymede, Callisto, Titan and Triton are the large moons with thick enough ice/water layers to make bulk high pressure ice phases a realistic possibility. Ref. 2 explores the possibilities of using seismic measurements to identify phase structures on icy moons, for example suggesting that an Ice VI layer could be detected beneath a liquid water layer. Different ice phases would be distinguished by their higher densities and thus higher wave propagation velocities versus the ordinary stuff now (January 2019) on the ground in Chicago. Such ice/water structural analysis is motivated by the prospect of underground oceans supporting life and how the presence or absence of ocean-bottom ice phases would impact this possibility. So ... Stay tuned.

1. O. Tscauner, S. Huang, E. V. B. Prakapenka, C. Ma, G. R. Rossman, A. H. Shen, D. Zhang, M. Newville, A. Lanzirotti, K. Tait (2018). "Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle". Science 359 (6380), 1136-1139. https://www.science.org/doi/10.1126/science.aao3030.

2. S.C Stähler, M. P. Planning, S. D. Vance, R. D. Lorentz, N. van Driel, T. Nissen-Meyer, S. Kedar (2018). "Seismic propagation in icy ocean worlds". Journal of Geophysical Research: Planets, 123. https://doi.org/10.1002/2017JE005338.

The discovery was published on 09-Mar-2018 in Science Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle

Where, and how, else might high pressure ice phases be found? Europa, mentioned in another answer, is not a good candidate because it is not all that icy; its ice layer is too thin to generate the needed high pressures (and we know of no processes similar to the formation of diamond-borne Ice VII on Earth). Ganymede, Callisto, Titan and Triton are the large moons with thick enough ice/water layers to make bulk high pressure ice phases a realistic possibility. This article explores the possibilities of using seismic measurements to identify phase structures on icy moons, for example suggesting that an Ice VI layer could be detected beneath a liquid water layer. Different ice phases would be distinguished by their higher densities and thus higher wave propagation velocities versus the ordinary stuff now (January 2019) on the ground in Chicago. Such ice/water structural analysis is motivated by the prospect of underground oceans supporting life and how the presence or absence of ocean-bottom ice phases would impact this possibility. So ... Stay tuned.

The discovery was published on 09-Mar-2018 in Science Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle, Ref. 1

Where, and how, else might high pressure ice phases be found? Europa, mentioned in another answer, is not a good candidate because it is not all that icy; its ice layer is too thin to generate the needed high pressures (and we know of no processes similar to the formation of diamond-borne Ice VII on Earth). Ganymede, Callisto, Titan and Triton are the large moons with thick enough ice/water layers to make bulk high pressure ice phases a realistic possibility. [Ref. 2](https:// doi.org/10.1002/2017JE005338) explores the possibilities of using seismic measurements to identify phase structures on icy moons, for example suggesting that an Ice VI layer could be detected beneath a liquid water layer. Different ice phases would be distinguished by their higher densities and thus higher wave propagation velocities versus the ordinary stuff now (January 2019) on the ground in Chicago. Such ice/water structural analysis is motivated by the prospect of underground oceans supporting life and how the presence or absence of ocean-bottom ice phases would impact this possibility. So ... Stay tuned.

References

1. O. Tscauner, S. Huang, E. V. B. Prakapenka, C. Ma, G. R. Rossman, A. H. Shen, D. Zhang, M. Newville, A. Lanzirotti, K. Tait (2018). "Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle". Science 359 (6380), 1136-1139. https://www.science.org/doi/10.1126/science.aao3030.

2. S.C Stähler, M. P. Planning, S. D. Vance, R. D. Lorentz, N. van Driel, T. Nissen-Meyer, S. Kedar (2018). "Seismic propagation in icy ocean worlds". Journal of Geophysical Research: Planets, 123. https:// doi.org/10.1002/2017JE005338.

Actually, Ice VII has been discovered in diamonds on Earth. The water is first trapped in the diamond as the latter is formed deep in the mantle. Then when the diamond cools at the surface its rigid lattice retains the high pressure in the interior enabling the water to reach a combination of temperature and pressure where it forms Ice VII. The presence of water in the deep mantle discovered in this way has significant implications for our models of heat transfer and tectonics within Earth and may even impact the prediction of earthquakes.

The discovery was published on 09-Mar-2018 in Science Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle

Fig. 1. Diffraction pattern of ice-VII in diamond M57666 from Orapa. Black crosses are data points; the Rietveld refinement based on this pattern of the type material (blue curve) converged to a weighted profile refinement parameter Rwp of 5.72% with a profile refinement parameter Rp of 4.57% and with c2 = 1.71 for 1398 observations. The structure factor–based refinement parameter RF was 4.0% (see table S3). The green line indicates the residual of fit. Blue tick marks denote symmetry-allowed reflections of ice-VII; olive tick marks denote allowed reflections of (Fe,Ni,C). (Fe,Ni,C) contributes 0.75 ± 0.05 volume percent to the pattern. The equation of state (27) allows estimation of the current pressure of this inclusion of ice-VII as 9.2 ± 1.6 GPa. The inset is a diffraction image of ice-VII. A diffraction image of ice-free diamond ~20 mm afar was used as a background image. Remaining single-crystal reflections are from the hosting diamond.

Where, and how, else might high pressure ice phases be found? Europa, mentioned in another answer, is not a good candidate because it is not all that icy; its ice layer is too thin to generate the needed high pressures (and we know of no processes similar to the formation of diamond-borne Ice VII on Earth). Ganymede, Callisto, Titan and Triton are the large moons with thick enough ice/water layers to make bulk high pressure ice phases a realistic possibility. This article explores the possibilitues is using seismic measurements to identify phase structures on icy moons, for example suggesting that an Ice VI layer could be detected beneath a liquid water layer. Different ice phases would be distinguished by their higher densities and thus higher wave propagation velocities versus the ordinary stuff now (January 2019) on the ground in Chicago. Such ice/water structural analysis is motivated by the prospect of underground oceans supporting life and how the presence or absence of ocean-bottom ice phases would impact this possibility. So ... Stay tuned.

Actually, Ice VII has been discovered in diamonds on Earth. The water is first trapped in the diamond as the latter is formed deep in the mantle. Then when the diamond cools at the surface its rigid lattice retains the high pressure in the interior enabling the water to reach a combination of temperature and pressure where it forms Ice VII. The presence of water in the deep mantle discovered in this way has significant implications for our models of heat transfer and tectonics within Earth and may even impact the prediction of earthquakes.

The discovery was published on 09-Mar-2018 in Science Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth’s deep mantle

Fig. 1. Diffraction pattern of ice-VII in diamond M57666 from Orapa. Black crosses are data points; the Rietveld refinement based on this pattern of the type material (blue curve) converged to a weighted profile refinement parameter Rwp of 5.72% with a profile refinement parameter Rp of 4.57% and with c2 = 1.71 for 1398 observations. The structure factor–based refinement parameter RF was 4.0% (see table S3). The green line indicates the residual of fit. Blue tick marks denote symmetry-allowed reflections of ice-VII; olive tick marks denote allowed reflections of (Fe,Ni,C). (Fe,Ni,C) contributes 0.75 ± 0.05 volume percent to the pattern. The equation of state (27) allows estimation of the current pressure of this inclusion of ice-VII as 9.2 ± 1.6 GPa. The inset is a diffraction image of ice-VII. A diffraction image of ice-free diamond ~20 mm afar was used as a background image. Remaining single-crystal reflections are from the hosting diamond.

Where, and how, else might high pressure ice phases be found? Europa, mentioned in another answer, is not a good candidate because it is not all that icy; its ice layer is too thin to generate the needed high pressures (and we know of no processes similar to the formation of diamond-borne Ice VII on Earth). Ganymede, Callisto, Titan and Triton are the large moons with thick enough ice/water layers to make bulk high pressure ice phases a realistic possibility. This article explores the possibilities of using seismic measurements to identify phase structures on icy moons, for example suggesting that an Ice VI layer could be detected beneath a liquid water layer. Different ice phases would be distinguished by their higher densities and thus higher wave propagation velocities versus the ordinary stuff now (January 2019) on the ground in Chicago. Such ice/water structural analysis is motivated by the prospect of underground oceans supporting life and how the presence or absence of ocean-bottom ice phases would impact this possibility. So ... Stay tuned.