More rainbows from silicon chips

Picked up at Junk Independence Day, these are unencapsulated silicon chips. You can make out the solder pads around the top edges, and I think the two solid blocks are PROM storage. The chips are supposedly Mosel MSS1002-14T speech generator ROMs from 1991.

To give an idea of scale, the outside walls of each cell are 3.8 mm / 0.15ʺ.

Here’s another photo, taken through a very cheap 8× loupe with a cellphone camera:
Silicon Rainbow