I used a fresnel lens to melt the surface of the stone to glass 
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Interesting! What kind of stone melts to glass? Granite? - Rich
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Anthropologists a thousand years in the future will apply for grants to further study this strange penguin-cult and the effects of their religious beliefs of 31st century politics. Love it.
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Igneous or as I like to think of it lava rock. Concrete cement and bricks work too 
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This rock was not perfect. The rock would flake off exposing new surface over and over. That is why the lower left quadrant is like that.
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Sandstone would be perfect for this. I have countertops in my kitchen that are nothing more than sandstone that has been melted in the earth (ok, with tremendous pressure too). It is truly beautiful quartzite. - Rich
Quartzite (from German: Quarzit) is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts.
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What the…? Did you stand over that thing and hold it? (Sweeeet!) 
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That’s really neat… what size is your fresnel lens?
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I made a holder and usually held the stone which after a while got hot 
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One square foot 50 rings per inch if I remember
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I agree what the…
The rock got hot! 
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Wow! Next project: fresnel mount with x-y positioning gizmo based on closed loop with a camera filtered all to heck.
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But not before they have further dissected the implications of fish worship and the four story tall muskie that was the center of our religious and political culture.
When you consider all the weird things you could find after we’re all long, long gone you kinda wonder if the Sphinx wasn’t just a roadside burger stand.
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Awesome! I once accidentally lit another child’s pants on fire (very briefly!) when I took a fresnel lens to school. Easily the naughtiest thing I did in my entire grammar school career.
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I’m such an awful person, because that first sentence made me laugh out loud.
I’m assuming you would have mentioned if the kid was injured in any way.
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Ha! No, he wasn’t injured in any way–the pants fire was very, very brief! I think he got a mild first-degree burn on the palm of his hand when he slapped out the fire on his leg.
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Ok, well I’m less awful in my own eyes anyway 
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I am thinking he was a liar…roflmao ?
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I burnt a spot on my finger when I forgot where the focal point was! The point itself did not hurt but the area around it did! My guess is that I “cooked” that spot to non-use but the area around it was only slight damaged 
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have definitely been burned by a glass of water sitting at the right angle in the sun. Kept thinking I was being stung or bit by an insect.
I have heard rumors about wildfires that were tracked back to an empty coke bottle, but found nothing about that in a quick search just now. Found this though!
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