We model tissue as a collection of point scatterers embedded in a uniform media, and show that the higher-order statistics (HOS) of the scatterer spacing distribution can be estimated from digitized RF scan line segments and be used in obtaining tissue signatures. Based on our model for tissue microstructure, we estimate resolvable periodicity and correlations among non-periodic scatterers. Using higher-order statistics of the scattered signal, we define as tissue ``color'' a quantity that describes the scatterer spatial correlations, show how to estimate it from the higher-order correlations of the digitized RF scan line segments, and investigate its potential as a tissue signature.