FMF - Friends of Minerals Forum, discussion and message board

[Ricardo Melendez]

Hi, some weeks ago we dig in a place where a lot of lightnings strike every year, thinking about some fulgurites could be formed in place.

found this rock, formed by coarsed grain sand, some look like quartz under the magnifier.

very similar as beach sand looks like.

the rock is solid and preserves it shape but some grains can fall easily when scratched with the nails, most not.

It could be a fulgurite?

[James Catmur]

To me it just looks like quartz grains centred together by some other mineral. Where did you find it in Guanajuato state?

[Pete Richards]

If it's a fulgarite, you might expect some melted and fused grains of sand around a hollow center.

[John S. White]

I believe it could be a fulgurite. With this type of fulgurite the glass would be in the center, surrounded by grains of sand. However, if the center is solid glass the object should be relatively heavy. The shape is hard to equate with a fulgurite though.