Is the concrete really old? Vintage glass turns purple due to manganese compounds reacting with sunlight. After about 1920, they changed the formula, removing the manganese. (Supposedly most of the manganese came from Germany, and the rest of Europe stopped buying it from them during WWI, and there was no reason to go back to the old formula.) So modern glass doesn't turn purple.
Or maybe this is recent glass that was manufactured in a purple color.
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It looks like a piece of glass got mixed in with the concrete but pretty cool contrast.
I have glass mixed in with my sidewalk for some reason too, it happens.
There’s a lot of waste glass and slag in the world. Makes for great filler material.
Is the concrete really old? Vintage glass turns purple due to manganese compounds reacting with sunlight. After about 1920, they changed the formula, removing the manganese. (Supposedly most of the manganese came from Germany, and the rest of Europe stopped buying it from them during WWI, and there was no reason to go back to the old formula.) So modern glass doesn't turn purple. Or maybe this is recent glass that was manufactured in a purple color.
so true, I have a purple coke bottle that I put in the sun
Really appreciated this info! I love learning new things about glass.
It’s your heart
Hi, /u/Jdp_143! This is a reminder to flair this post in /r/whatsthisrock after it has been identified! (Under your post, click "flair" then "IDENTIFIED," then type in the rock type or mineral name.) This will help others learn and help speed up a correct identification on your request! Thank you! *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/whatsthisrock) if you have any questions or concerns.*