It's made of little vertical crystals, the crystals look like sugar, some parts of the rock reacted to acid solution. I found it in İzmir/Turkey. What could it be?
Your description, the reaction to acid, and the pictures would be consistent with calcite in quartz, together with some staining from iron impurities to create the coloured veins.
Your description, the reaction to acid, and the pictures would be consistent with calcite in quartz, together with some staining from iron impurities to create the coloured veins.