This is a large painting, exploring blue (in various hues). The overall effort is to create a transparent effect, where the viewer can see through, into the depths beyond.
The foundation palette is umber/burnt sienna, applied in random strokes across the surface, in light and dark shades. From there, it is a process of applying small bits of colors - all tinted with umber/burnt sienna. There are many colors, but the emphasis is on blues: cobalt blue, cerulean, ultramarine, also warm and cool greens.