Originally Posted by scatterax
but i also think he incorporated the cube somehow.
I surmised that the element Tony was able to create from Howard Stark's schematics was one that was in the Cube. Howard analyzed the Cube and must have been able to detect the then-unknown element but was unable to synthesize it with the technology of his time. Tony had the equipment and expertise to re-create it in his laboratory.
Fury, having the Cube in his possession and also having discussed things with Howard Stark, knew all this. His reasons for not telling Tony everything about the Cube must have been related to security. SHIELD didn't yet understand exactly what the Cube was or its origins, so they would naturally want to limit the number of outsiders who were informed of its existence.