What is "Porphyry" in concrete mix design?

In terms of Concrete Mix Design is "Porphyry" a trade name for a specific stone or a type of stone with certain properties? This would be specific to UPHC Concrete mix. I would like some assistance in understanding this term in relation to Concrete mix design. If I were to be mixing a UHPC and had all... show more In terms of Concrete Mix Design is "Porphyry" a trade name for a specific stone or a type of stone with certain properties? This would be specific to UPHC Concrete mix. I would like some assistance in understanding this term in relation to Concrete mix design.

If I were to be mixing a UHPC and had all the components, would I use "Porphyry" as the Aggregate or a stone with similar properties to a "Porphyry"
Update: I am familiar with Porphyry as a stone name, its properties etc, but in terms of Concrete Mix Design it seems that this is a genaric term. Anyone familar with Concrete engineering and its generic terms?
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