Sounds like a new idea. I have never seen that done before it could be interesting another idea you may use is with square white spindles and wrought iron black medallion inserts in between would be very attractive and a custom look. Then to carry the look a wrought iron chandelier near by would be beautiful. I like the idea of white risers on the stairs with that look.

I've never seen that but it sounds very interesting. If you decide to do this, buy a few different styles to play with before installing. I would think a very plain, straight lines, white spindle with a slightly ornate iron one, so they won't compete.

Here is one photo with white post and wrought iron spindles, which is not exactly what you are doing, but just to give a feel of how it looks with the 2 materials side by side.

Thanks! I have been looking at that picture. The people that are installing the stairs suggested the mixture of spindles and I have never seen or heard of it before.

Have a look at this pic. I know it's not exactly what you're thinking of doing, but you get an idea of the mixed wood with wrought iron.

The idea is interesting and unique, however, your primary consideration should be the overall design of the space. If the idea fits within the context of the room, all of it's positive qualities will work in your favor, and vice versa.
What will be the colors of the walls - will they bring up the white spindles?
How close and frequent are the contrasting elements, and how does viewing the stair at a sharper angle change that balance? (closer together)
Will other elements in the room have a similar theme of contrast?

You can reach a good balance with these elements, but it will take some planning and precision.

I've attached a classical example from the Hermitage Palace. The main theme is black on white, but there's also a play on orange/gold - the stone walls of the lower space, the golden handrails and highlights, and a repetition of all these elements in the tiles.

Hope this helps! - AN