where λ° = 70Å, k = 107.3 and t is time in days. Thermal histories of lunar basalts 15597, 15499 and 15058 estimated with the lamellae coarsening speedometer are comparable to those estimated from grain size.
In the Apollo 15 QNBs three lamellar orientations dominate; (100) and two sets of (001). Heterogeneously nucleated (100) and (001) lamellae grow with C2/c symmetry, but the homogeneously nucleated (001) lamellae grow as coexisting C2/c and P21/c. All orientations form over a restricted temperature (1100–1066°C) but have different orientations as a consequence of the change in cell dimensions that occurs during the C2/c to P21/c transition.