strange petrified ondular patterns in a rock

[tlatoanitzin]

I found this rock over a small promontory of earth and boulders near my house, there are many fragments of limestone and strangely I have found many small river stones in the area. The rock in the photos has this kinda coat of petrified material, it resembles mud at sight, I soaked it in water and even brush it, but the material is very hard and cannot be removed. Could it be a fossil or mineral?
All sizes | 1802201312001 | Flickr - Photo Sharing!
All sizes | 1802201311991 | Flickr - Photo Sharing!
All sizes | 1802201311992 | Flickr - Photo Sharing!
All sizes | 1802201311993 | Flickr - Photo Sharing!
All sizes | 1802201311994 | Flickr - Photo Sharing!
All sizes | 1802201311995 | Flickr - Photo Sharing!
All sizes | 1802201311996 | Flickr - Photo Sharing!
All sizes | 1802201311997 | Flickr - Photo Sharing!
All sizes | 1802201311998 | Flickr - Photo Sharing!
All sizes | 1802201311999 | Flickr - Photo Sharing!
All sizes | 1802201312000 | Flickr - Photo Sharing!

 

[wvwildman]

where are you at what state?

 

[old digger]

Welcome!
Can you post your photo's in a more friendly way, instead of going back and forth thru the net. Your photo's could be a slight smaller also. Thank You!

 

[tlatoanitzin]

I found it in Tijuana, Mexico. Here is the set photoset with more reduced images. Thanks in advance.

 

[wvwildman]

looks like lava

 

[tlatoanitzin]

Indeed, it looks like melted lava, thank you all.