Figure F13. Correlation of grain size between plagioclase, olivine, and clinopyroxene as measured in 146 thin sections of relatively undeformed samples using a micrometer ocular for scale. Olivine gabbro includes troctolitic gabbro, gabbronorite includes orthopyroxene-bearing gabbro. A good correlation between the grain sizes of the three minerals is apparent except for the coarser grain-size range (>15 to 20 mm), where the correlation is less clear. This breakdown at higher grain sizes is probably the result of the truncation at the limit of the thin section of larger crystals. A. Olivine vs. plagioclase. B. Augite vs. olivine. C. Augite vs. plagioclase.