Friday's Focus - 2019/10/25 - Rocks

Ken Rennie

Well-Known Member
A few from me. Firstly 2 from Northern Spain


Now 2 from Northern Scotland


Lastly a very quirky take on rocks from Luxembourg where people have been hollowing out the rocks here to make millstones since the middle ages. This is called Hohllay or Hollow Rock, the man made cavern is approx 4,000 sq ft in area.

I have seen a few rocks in my day that are really beautiful. Here are four examples.

A close-up of sandstone with iron oxide cementing the grains in colorful patterns near Kanab, Utah.
Wonderstone, iron stained sandstone near Knab, UT.jpg

A rhyolite porphyry with pink feldspar crystals and blue quartz crystals near Llano, TX.
Blue quartz rhyolite, Llano, TX.jpg

A breccia in Mosaic Canyon in Death Valley National Park, CA
Mosaic Canyon brecia, Death Valley, CA.jpg

An intricately folded and banded iron formation with hematite (gray) and jasper (red) layers near Ishpeming, MI
Banded iron formation, Ispheming, MI.jpg
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