Tested with a Raman spectrometer and it came back as natural quartz. The shape is off to be lab grown.
Pretty internally clean, looks like could be slabbed or faceted easily. Neat block formation, though I do have some larger not in the same shape.
This material is super vintage and came from an old old collection. Rare to see natural quartz like this.Probably could use for doublets/triplets or in manufacturing. If you have questions please ask.