41. Layered peridotites are igneous sediments and form by mechanical accumulation of dense olivine crystals. 42. Consequently, Fe 2 + can replace the magnesium ion in the olivine structure. 43. Oxidation of Olivine ( FeMgSiO 2 ) releases Fe, Mg and Si ions. 44. These particular ringing rock boulder fields formed from a rock type called olivine diabase. 45. Both the normal and olivine diabase rocks are dark grey to black in color. 46. Their black augite and yellow green olivine are also easily observed in hand specimens. 47. In the A-type asteroid with a surface consisting of almost pure olivine . 48. At St Marys there were two volcanic eruptions of alkali-olivine basalt at. 49. From near Hobart there is olivine basalt from. 50. This allowed it to detect the presence of quartz, olivine , and hematite.
