Howdy from the US- I'm in Massachusetts and have recently come across the gritweed issue- hadn't heard of it before, and there hasn't been any mainstream news coverage of the issue here.
First of all some background: I'm not a heavy smoker, but tend to be regular, and in the past year I started having mild chest pains which I felt were likely from smoking. I switched to a bong which seemed to help. During a visit to my sister I experiencing her awesome vape machine, so I got a vape tube (not the expensive electric or butane kind, just an unfiltered pyrex two-piece deal that you use with a lighter or in my case, a candle) and started using it, thinking I was doing something good for my body by cutting down on tar. But after using this for a couple months my chest pains came back worse than ever, and I gave up smoking altogether. The troubling pains have continued, along with shortness of breath and fatigue, so I went to the doctor thinking maybe I had bronchitis or a bacterial infection, but no sign of any such was found (although I will get additional tests).
I've been doing my own research to try and figure out what is wrong with me. My symptoms are similar to silicitis, and in looking into that I ran across a reference to gritweed on wikipedia, and that led me to this forum.
About the stash: The stuff I've been smoking looks normal and no dust is visible, although possibly the count was small for the weight. The buds are hard and compact, although I was told they were fresh. When a small amount is chewed there are tiny bits of grit that crunch in my teeth- just a few, but present in two tests from different parts of the herb.
The source is a close friend, but where he got it I don't know. I want to make sure I know what I'm talking about before get into the subject with him. He is not all that choosy about his connections, from what I've seen, so it could be imported, but I got the impression it was locally grown.
People have been talking on forums about how the silica or ground glass is "sprayed on" to increase weight and also that it is attached using "some sort of glue" to make the buds look sparkly.
However, I know that silica sand is considered a cheap alternative to using silica gel packs as a dessicant. Although most intelligent people would know enough to use it as an *environmental* dehumidifying agent, reather than letting it touch the herb, silica sand is commonly used to dry decorative plants by burying the entire plant in the sand. Clearly, if some bonehead stoner got the bright idea to do this with their green pot, sand would permeate the buds, and no amount of shaking and straining would ever get it all out. Plus if very fine silica sand were being used in the environment and causing airborne particles, these could easily adhere to the sticky resins in the pot, no glue required!
Now, I bring this up because I actually found a blog post (a pretty old one) where somebody was asking if using sand directly on the buds was a good idea. And although the poster was ultimately discouraged from doing so, nobody who responded to that post seemed to understand the possible dangers, since sand is something we usually think of as benign.
The possibility that large-scale commercial growers in black-market-driven countries are engaging in a common practice of maximizing profits by curing their buds via immersion in sand, is of course disturbingly easy to imagine. But I am also wondering if anybody out there knows someone who has done or is actually doing that with their homegrown, in ignorance of the hazards.
And if anyone is thinking about doing it, please don't!
Thanks, and looking forward to your thoughts.

I would grow my own if I was you. I've never contaminated my weed before but it sounds bad. I really hope you get better.