is it possible to create this kind of material with the standard textures? The Voronoi texture (set to cells) is coming close but I don’t know if it is possible to a) set the single cells apart from each other and b) to give them seperate colors.
Just switch a Voronoi texture to Cells coloring, and drive it through a Color Ramp node set to Constant interpolation mode.
Adjust the Color Ramp stops to the desired color ratio so that the amount of colored flakes is close to the reference image.
You would generally want narrow black, orange and green strips, over a broader white background, so adjust proportions accordingly.
Speckle size can be adjusted from texture scale parameter. Changing size may also require adjusting color stop positions.