Understanding the processes that govern whether a coral reef is accreting (growing) or dissolving are fundamental to questions of reef health and resiliency. The Reefscape Characterization task of the Coral Reef Ecosystem Studies (CREST) project is focused on geochemical, geologic, and metabolic processes that affect carbonate precipitation and dissolution on coral reefs. For the 1-km x 1-km study site around Crocker Reef in the Florida Keys, 52 surficial sediment samples were collected and processed to yield grain size and mineralogical data. Samples 1–35 were collected in July 2013 and and samples 36–52 were collected in July 2014. Grain size data are reported on a percent-weight basis for phi (Φ) sizes ranging from -2 to 12.