Main site is a 2m cavity in remote heathery country. It was lined with quartz crystals, but has now been stripped bare. Nearby is smaller cavity, and 100m away a seam of quartz has been exploited at the base of a small outcrop. Appears to be in rhyolitic tuff. The occurence of the quartz is as the so called Alpine Fissure Style Veins.

The cavities are believed to be naturally formed and not excavated.

Collecting of all sorts was in vogue with gentlemen of leisure at the start of the 19C, and mineral and crystal collecting was part of this. Rock crystal samples marked as coming from Snowdonia or Beddgelert - called Snowdon Diamonds were often found in collections. Some samples in the National Museum of Wales are attributed to the same source, but none are beleived to come from Moel Meirch - Mynydd Drwsycoed being thought to be a likely source.

The nearest parking is at the small car park for Y Cnicht climbers, opposite the slate quarry. Walk back up the road to where it sharply turns left downhill. Take the track on the right towards a house, then follow the footpath to the right, which leads uphill and eventually reaches the base of cliffs. Continue left along the wall into the Afon Cwmedno valley. The cliffs can be ascended via a steep path onto wet, rocky ledges. Follow indistinct paths to where the valley opens with Moel Meirch on the left.

There are no proper paths up Moel Meirch. You can either continue up the valley and approach from behind or take a more direct route by following the stone wall to the left until it turns 90 degrees. From here, ascend directly, avoiding rocky slabs by sticking to the heather. Be cautious of hidden obstacles beneath the heather. A GPS is useful, and there’s good signal coverage (at least for EE).

The crystals have already been removed. There are some quartz sections left, nothing worthy of being taken, so leave intact, so there it at least something for future visitors to see.