Framboid size-frequency plots show log-normal distributions with a geometric mean diameter of 6.0 μm and with 95% of framboids ranging between 2.9 and 12.3 μm. The largest framboids may be 250 μm in diameter, although spherical aggregates of framboids, known as polyframboids, may range up to 900 μm in diameter. Various spherical clusters of nanoparticles have been described which are less than 0.2 μm in diameter. These do not form a continuum with framboids. There is no evidence for any significant change in framboid diameters with geologic time, and the differences in mean sizes between hydrothermal and sedimentary framboids do not, at present, appear to be statistically significant. By contrast, it appears that the mean diameters of framboids from non-marine sediments are significantly larger (7.6 μm) than marine framboids (5.7 μm). There is some evidence that framboids formed in the water column are smaller than those formed in sediments, but the non-critical use of this possible difference as a proxy for paleoenvironmental reconstructions is not robust. So-called microframboids and nanoframboids are discrete entities which are distinct from framboids. They are nanoparticle clusters and are not produced by the same processes as those involved in framboid formation, nor do they behave in the same way. They are more akin to atomic clusters, which form similar constructs.
Comparing Mean Vectors Via Generalized Inference in Multivariate Log-Normal Distributions ns