Many of his work were exhibited and are permanently located at the Museum of Modern Art, in New York; the San Francisco Museum; the Institute of Arts, in Chicago; the Modern Art, in Paris; the Art Gallery, Stockholm; Bienal Americana, in Mexico; Bellas Artes, Argentine.

Mariano is often called a "magician", who converted nature's light and forms into a beautiful object. He was a "rebel" against all modern trends already established in his time. A trend that would not give way to any new form of expression. In 1941 started working on his "gallos",- roosters that gave him great popularity and one of them were acquired by the New York Museum of Art.

He have said: "I consider myself more an expressionist than an abstract artist, since the abstract is foreign to reality and the artist con only give it texture and space; although I always start from reality, always thinking of it and in my themes". This is true.