Obsidian has one characteristic that slag generally lacks – a hint of translucence.

On our recent Antiquities Tour, Rich and I came across interesting rocks on an abandoned railroad bed in Eastern Colorado. The chunks looked like obsidian. They fractured like obsidian and had the feel of obsidian. But, they didn’t quite look right. But blue and pretty!  So, we put a bunch in the car. Rich was excited.

One of my geologists colleagues confirmed my observation on the fracturing and glassy feel of the rocks. But, they didn’t have the slightly translucent look of obsidian. Still I like them. So, I gave some to friends.

One scientist friend, Linda Mueller, appreciated the rock and investigated further. Here is our conversation on FB.

“I’ve been asking around about the rock you gave me. The consensus seems to be that the colors indicate that it’s slag glass and not obsidian. Certain areas in Colorado use it as railroad ballast.  Obsidian and glass slag are so similar that it’s often difficult the tell the difference. Unscrupulous ebay sellers have taken advantage of this and have sold the artificial form as the real thing.

“Anyhow, whatever it is, I’m still fascinated by it. It’s beautiful and it will remain on my desk as a paperweight.  Thank you again for it.”

I replied, “Thanks for checking this out!”

Linda added, “I was hoping for something interesting like turquoise. Still the stone is calming in a odd sort of way. It’s cool to the touch and smooth among the rough (parts).”

My thought: “Maybe good energy can come from slag. Say, that might be a good blog!  Help me write it?”

So Linda did the work!

Linda:  “I think so. The rock is truly entrancing. I can’t explain it. From the moment I saw it, I was fascinated by it. It was a special gift. I truly mean that.

“When you think about it, it does look a lot  like obsidian, which is volcanic glass. I can’t remember what you said the spiritual properties of obsidian are but I wonder if they mirror the history of the stone? A huge amount of geothermal energy is needed to create obsidian. It flows from a volcano, then cools and solidifies. Tension moving toward calm? (Great analogy, I thought!)

“Glass slag is similar to obsidian; it, too, consists mainly of silica dioxide. It’s formed by heating ores (rock) to high temperatures. It’s a human-made rock, but it’s not a new technique. Humans have been creating it since the late bronze age (1500 – 1000 BCE). At least three thousand years!  Wow!  Ancient man found other uses for the leftover glass slag. They recycled it even then. Somehow we lost sight of that when technology gave us easier ways to make glass and pottery.  Now we’ve come full circle and have found uses for it again.

“Might glass slag have properties similar to obsidian since the two are so similar?  When I hold the rock, I feel calm.  It takes away tension.  The coolness and the weight of the stone is comfortable.  Like obsidian, it was formed from heat/molten rock (tension) and it’s present state is cool/solid rock (calm).

“When you think about it, it fits. You and I have a strong interest in preservation, recycling, taking care of the earth. The rock cries out:

“‘Hey, look at the beauty and usefulness I have!  Quit taking rocks from the earth to crush for railroad ballast when you already have me. I was needed for another purpose and now that it is complete, I’m moving on to my next one.’

“Everyone I’ve shown it to has had positive reactions to it. I wonder why that is?”

So, our on-line conversation ended here.  But perhaps readers can weigh in and add to this. Obsidian or Slag – What Does it Matter?

The gift had the intention of love, perhaps that is a clue.