I am working with collagen matrix implants that are generating some localized bone formation adjacent to the implant site, and am looking for a biological stain that will differentiate nicely, the bone from the implant. The samples are fixed in formalin, decalcified (sodium citrate - formic acid), and processed into paraffin blocks. I have tried Masson's Trichrome which stains the implant as well as the collagen content of the bone the same color. Standard H&E clearly shows the different morphology, however it would be nice to stain the two components with different colors.