Your new Iridescent Altar is very different from your old altar. Not only does it require Crystals during crafting, this Crystal MUST be attuned. It also requires you to place items around the Altar in order to craft anything. When placing Attuned Crystals into the Altar you will notice that at night, the Constellation that the Crystal is attuned to will display on the floor below the Altar. The crafting grid is also much bigger.

Attuned Crystal in Altar

The above Altar has Spectial Relays that are far to close, do not do this.

When looking up new items to craft you will notice that there are other items outside the crafting grid:

Iridescent Altar crafting grid

Instead of crafting only within the table, you are also using the area around the table to craft. During the crafting process your Iridescent Altar will tell you what items are required to continue crafting and to finish item. In order to do this you have to use Spectral Relays.