What gems could be found in an underground pond or river?

[John Carroll]

I have the party in an underground cave that has a river in it. I've done a search, but haven't found a good answer.

I've read books where gems fill an underground cave deep in the Earth. I'd like to do something similar, but I want to be a little more realistic. What sort of gems might be found in a cave like this? What could I BS my way through if it's unlikely?

I could certainly do quartz and I think amythest goes with that, but is there anything else?

[DixieGal]

Usually, gems are tightly embedded in a black matrix. You might be able to have veins of gold glimmer in the lakebed, but the gemstones should sparkle from the cave wall. Or use fluorescent minerals, which glow under backlight in vivid neon colors.

Gemstones are like glass and can cut you deeply. Probably would not something you want to walk on or lean against.

When I hunt gems in water, they don't gleam or anything. They are mud clumps. You dig out the shovels full of mud, then start washing it away, breaking up the mud clumps, until it dissolves and washes away, hopefully leaving behind something shiny.

[John Carroll]

Originally Posted by DixieGal

Usually, gems are tightly embedded in a black matrix. You might be able to have veins of gold glimmer in the lakebed, but the gemstones should sparkle from the cave wall. Or use fluorescent minerals, which glow under backlight in vivid neon colors.

Gemstones are like glass and can cut you deeply. Probably would not something you want to walk on or lean against.

When I hunt gems in water, they don't gleam or anything. They are mud clumps. You dig out the shovels full of mud, then start washing it away, breaking up the mud clumps, until it dissolves and washes away, hopefully leaving behind something shiny.

Blah. I was afraid of that. I think I'll go with quartz. My son and I went to the Denver Museum a few weeks ago and looked at information about quartz caves. I think that'll work and I'll just have it on one wall.

[DixieGal]

Maybe the cave could actually be a giant geode? With amethyst or citrine crystals covering everything?

[John Carroll]

Originally Posted by DixieGal

Maybe the cave could actually be a giant geode? With amethyst or citrine crystals covering everything?

That's not a bad idea, but I want them to spend the night there and the insides of geodes are pointy. *grin* I'm okay with just making half of it crystal.

[Luke King]

I know it's not a gem, but surely there could be gold in the river.

[John Carroll]

Originally Posted by Luke King

I know it's not a gem, but surely there could be gold in the river.

There definitely could and I may add that. I'm not certain. I wanted something a person could pick up and suddenly have treasure.

[Worldwalker]

Remember that your cave has a river running through it, so it could have any gems that would normally be found in river gravel (alluvial deposits).'

As far as the cave itself, consider its geology. Your typical cave is limestone, so any gems found in it would be those which could be found in limestone. You might want to do a bit of searching to find out what gems have been found in existing caves.

If you can work the quartz in there (my resident geologist isn't available, by the way, so I'm not sure if the quartz is possible) remember that it comes in many colors. However, most of them aren't particularly valuable, and few large pieces are gem quality.

[ardeegee]

Originally Posted by Worldwalker

As far as the cave itself, consider its geology. Your typical cave is limestone, so any gems found in it would be those which could be found in limestone. You might want to do a bit of searching to find out what gems have been found in existing caves.

He could go with lava tubes, which are a good place to find crystals and gold. In fact, that is what a gold mine typically is-- a vein of solidified magma that has gold mixed in with quartz. As the magma flows through the tube, quartz and gold precipitate out of the melt early. The tube could completely fill with solidified magma, or it could remain hollow in the middle. Presto-- cave filled with various types of crystals and metals.

http://en.wikipedia.org/wiki/Quartz_reef_mining

http://www.google.com/images?um=1&hl...=&oq=&gs_rfai=

[Worldwalker]

Is a gold mine solidified magma, or a hydrothermal fluid that has seeped through cracks? I think I'm going to have to get the geologist involved here when I can.

[James_Wilde]

If your party has found his way into this cave, couldn't someone else have done the same thing earlier? A robber hiding his stash, a pirate captain his hoard, etc.

[John Carroll]

The series of caves there in is completely untouched by anyone, so hidden treasure won't work for the story line. The idea is to have a cave that is sparkly. *grin* This is what I wrote (note: the insects and plants are bio-luminescent) ---

A few minutes later he found a good sized cave with a river running through it. The truly amazing detail about the cave was that it sparkled brightly in the glowing light of the underground flora and fauna. The sparkling effect came from quartz crystals that filled the right side of the cave.
“Ohh, pretty,” Vevin said appreciatively from behind them. It really was beautiful. Insects and tiny birds flitted about the cave, many landing on the crystals. Every little movement made little dots of light dance around the cave. It all seemed so alive.

[AndrewH]

Originally Posted by John Carroll

A few minutes later he found a good sized cave with a river running through it. The truly amazing detail about the cave was that it sparkled brightly in the glowing light of the underground flora and fauna. The sparkling effect came from quartz crystals that filled the right side of the cave.

I would consider re-writing this. 'The truly amazing detail' is too much like an 'as you know Bob' speech.

I'm probably alone in this, but I'd be curious to know more about these underground plants. Do the crystals act as natural light tubes from the surface, or generate their own light? Or do the plants operate on something other than photosynthesis? Chemosynthesis? (Cold seeps, hydrothermal vents, and whale falls are quite interesting.) Thermosynthesis? Magic-synthesis? Caves on earth are low-energy ecosystems, and without sunlight you're not going to find much more than maybe some algae or lichen on the walls.

[John Carroll]

Originally Posted by AndrewH

I would consider re-writing this. 'The truly amazing detail' is too much like an 'as you know Bob' speech.

*grin* this is the unedited version. I'll be going over that paragraph a few times and making it read smoothly.

I'm probably alone in this, but I'd be curious to know more about these underground plants. Do the crystals act as natural light tubes from the surface, or generate their own light? Or do the plants operate on something other than photosynthesis? Chemosynthesis? (Cold seeps, hydrothermal vents, and whale falls are quite interesting.) Thermosynthesis? Magic-synthesis? Caves on earth are low-energy ecosystems, and without sunlight you're not going to find much more than maybe some algae or lichen on the walls.

Please keep in mind that I'm not a scientist, and I'm not trying to convince a scientist of anything. I'm explaining enough that a casual reader can say, "okay, I'll go with that"

These are excerpts that kind of explain it, basically, it's a magically enhanced bio-luminescence much like in a firefly. Their blood/sap glows and they have transluscent skins:

The temperature became gradually cooler as the party traveled deeper into the ground. Soon plants began to appear on the walls and ceiling of the tunnel. These plants were extremely rich with oxygen, which made it possible to breathe the air.
The plants glowed as well. Bioluminescent fluids moved slowly through them. It was similar to the glowflies in the forest, but much more powerful. They were different than plants on the surface. Their powerful roots dug through rock easily, but at the same time, it secured the stone so that ribs and braces were no longer needed to keep the tunnel secure.
Plants that grew in the ceiling and walls of caverns and tunnels tended to be unfit for human consumption, though Rojuun could eat many of the varieties. The roots collected nutrients from deep within the rock. This made them metallic and heavy in a way that humans could not digest. The floors of Rojuun caverns often had softer and more fertile dirt brought in by extensive underground rivers flowing throughout the world of Ryallon. The ceiling and wall plants often ground rock to dust, which fell to the floor adding more dirt.
From this softer dirt grew plants edible to humans. They glowed and produced copious amounts of oxygen as well, but were softer than their hanging counterparts. Animals of all sorts fed upon them. Meanwhile; other animals fed upon those animals. When the animals died, they lay in the soil adding their nutrients to it. It was a vast cycle of life underground that had taken thousands upon thousands of years to develop. From that life came the Rojuun, later than humans had developed upon the surface, but perhaps that was the way the gods intended it.

“So, do you know why the animals underground all glow?”
“Of course. It’s so they have light to see by. Why else would they glow,” Vevin replied, rolling his eyes again. The liquid silver rippled in a circle.
“Ahh,” Sir Danth said, nodding. “That makes complete sense.” Tathan and Liselle nodded too, after all, why else would the creatures glow.

[queentess]

Originally Posted by AndrewH

I would consider re-writing this. 'The truly amazing detail' is too much like an 'as you know Bob' speech.

The cave interior sparkled like tiny stars, the quartz in the walls brightly reflecting the glowing light of the underground flora and fauna.