I just realized that I meant to include one of these photos in the main post about the breccia at Devils Gate, near Eureka, NV. Instead of one extra photo, I hereby give you three.
The matrix between the dark gray limestone breccia fragments consists of coarse-grained white calcite, with the calcite crystals intergrown in a fashion that I've not seen before.
Here's a photo zoomed in on crystals near the tiny bush in the previous photo. This time my boot barely made it into the photo.