I wouldn't do it. I'm not a big fan of mismatch, though it is currently a trend.

I am a fabricator.

slightly unusual - yes. "Odd" is too harsh a word. If it's what you want and you are clear on the difference in the various material options (natural stone, engineered stone i.e.quartz, and solid surface like Corian,) the do what you like. You may find it requires 2 fab shops since the process machinery for natural and engineered stone is different that what is used for Corian. Only a very large fab shop typically has the process machinery for both.

I'm not a big fan of this combo, but if I did it I would be more tempted to use the Corian on the perimeter and the granite on the island. Corian is usually less busy than granite, so making the granite's pattern a feature on the island, while having the quieter pattern of the Corian around the edge would seem to me to be a more effective way of combining them. OTOH, if both are going to be surfaces without busy patterns (like an absolute black honed granite on the perimeter and a plain white Corian on the island) then I think it wouldn't matter which way you used them.

If you decided to mix materials, my only input would be to choose a Corian that is not trying to look like stone. Get a solid or lightly/faintly patterned solid surface. Otherwise, the difference between the materials will be highlighted.

Have you ever seen wood-look laminate flooring installed next to real wood? By itself, laminate looks fine, but next to real wood it is not as attractive.

I can see using a section of solid surface to take advantage of its positive attributes.

I happen to have the granite / Corian combination in my kitchen, breakfast and family room open concept area. It works well for the reasons already listed above. The backsplash is the focal point so all counters selected were muted. All cabinets and the fireplace mantle are KM Biscotti with cocoa glaze (cream). The kitchen counters and fireplace surround are Dakota Mahogany (black, copper, gray speckles). By happy coincidence, the Corian in Ecru exactly matches the cabinets and reads as a solid although it has light veining. Corian counters were installed on the coffee bar in the breakfast room and on the display/desk cabinet area in the family room. I did use different companies for the two counter materials.

My reasons for changing to Corian were that I wanted a lighter, more formal counter in the family room. Also, the counter for the coffee bar had to be easily removable as this area conceals a side by side dryer and a top loading washer. The Corian is four separate tablets that span wall to wall The point is that using both granite and Corian can be nicely mixed, but not easily, to allow the area to flow as one. I used both the consultant at HD and an ASID interior designer for my remodel.

As an aside, if you're considering Corian for an island, please be aware that it scratches easily. The installers advised me that to avoid this from happening, hard items (i.e, glass, metals, etc.) should be lifted, rather than scooted, from one area of the counter to another. Yes, scratches can be buffed out, but you should be aware of the nature of this material. I'm very happy with my selections, but my Corian counters only see light use. I know there are others who use Corian on their kitchen perimeters and will disagree with me about using it in an area that sees hard use. You could get some of those little samples at HD to experiment how it would work for you in action.

I realize this post is several years old. I currently have Corian but am contemplating Quartz for the island due to the reasons texasgal47 mentioned.....Corian scratches easily and our island is a mess. Our Corian is about 10 years old. I initially called fabricator about 3 years ago requesting they come and polish it. Apparently not a priority as I've called multiple times.

also curious what the OP decided - or if anyone has photos to share of this mix!

Thinking granite counter tops and corian back splash does that