Gold Veins thru Quartz - Pendant

At the time of purchase I was told this type of worked quartz with gold veins comes from California. Here is the question: did the quartz fill into gold formations or did the gold penetrate cracks in the quartz. Potentially a very delicate material and you probably won't see much of this available, I know I haven't. This is holed thru the sides, which are thick, so that a thin chain will pass thru. Dimensions are: 29 mm x 14 mm (max) x 7mm; 4.1 grams.