What a tempest in a pot of tea!
T-Grain by any other name is still Tabular Grain. These grains are very large in one dimension and very thin in another. There are twinned crystals which are basically 2 T-grains fused together, and there is epitaxy which is something stuck on the corners of the crystal, by any means convenient. Kodak and Fuji have both used this.
Other grains are cubic and octahedra. These describe the crystal habit, ie, cube or octahedral. There are also rounded cubes and octahedra, achieved by etching real cubes and octahedra with silver halide solvents. Then there are "K" grains or clunkers as we called them. These have no specific shape and resemble a mix of sand and gravel.
Any of the above can be core shell meaning that the core is one thing and the outer surface is another. You can also have a graded emulsion in which the core gradually blends into the surface. Oh, and y'all forgot to mention converted emulsions where one type of crystal is converted into another placing stress on the structure to gain internal and external speeds for direct reversal.
The one key is that as size and iodide content goes up, the crystal dissolves more slowly in hypo. As addenda on the surface goes up, the crystal dissolves more slowly in hypo. Thus, a highly sensitized, highly antifogged high iodide crystal of any shape will dissolve very slowly in hypo. It is just a fact that T-Grains with high iodide content are also high speed modern grain types and dissolve more slowly.
And, a T-Grain can be a hexagon, a triangle or any shape, as it is the thickness that denotes whether it is a T-Grain, not the shape of the grain.
PE
