Calcium carbonate nanoparticles are one of the most economical nanomaterials. However, the ease of agglomeration and lack of functionalities are obstacles to their widespread application. Here we report the preparation and characterization of the solvent-free fluids based on rhombohedral nanoparticles of calcium carbonate, with a soft organic shell on the inorganic particle surface. For the first time, solvent-free fluids based on an inorganic salt are demonstrated. The fluidity of this nanosystem derived from the soft shell will be of great value for processability, manipulation, and ease of dispersion. Moreover, the solvent-free fluids are intrinsically conductive, which is a new functionality for calcium carbonate nanoparticles. The core/shell structure is clearly revealed by the high-resolution transmission electron microscopy images, and this verifies the presumed structure of this family of functionalized nanostructures.