Images taken from the optical microscope were processed using ImageJ. The gray-scale images were de-speckled and filtered with a 1.5 pixel Gaussian blur to remove unwanted noise artifacts. The images were then binarized by auto-thresholding. The particle Area, solidity, Aspect Ratio and Feret min and max diameters were measured using the Analyze Particles function (16px 2 to infinity). For amorphous particles, the AR is a measure of the overall symmetry of a particle and solidity is a measure of empty space within the particles external volume (Supplementary Information 3). The measured area was used to calculate an equivalent diameter. The collected data was processed and plotted using Python software (numpy, matplotlib, pandas). For the scatter plots, a 2D kernel density estimation (seaborn) was used to better visualize the density of data points.