Tantalum makes me hungry

COAL CAVE

Pure Anthracite. Potentially flammable. Polished mirror-smooth in uneven shapes. Travellers have stepped to random sections of the wall and slowly rubbed their reflections into view. If you do this, and stare within the coal-glass for a time, angels will beckon you. They will come in strange phantasmagorial forms and silently promise secrets and revelations. No-one can see anothers angels. They are lies.

TANTALUM VEIN

There is an exposed vein of clearly valuable metal running in this cave. It could be quite handy in a number of ways. But is is quixotically placed. You are always a little too far from Tantalum to make use of it.

TITANIUM ETCHED BY FAILED BEHOLDER STRIKES

Braided by exposed titanium ore. The ore is pure. Its ripped with criss-crossed lateral diagonal lines in bright metallic discolour-stains. Imperial murderer-purple, witch-eye green, dark-sun yellow-red, pervslinger pink and boiling blue. The lines crosshatch negative-image manlike forms in shapes that suggest some distress. On inspection, the organic bleeds of colour into ore are quite beautiful.

NOT DARK NOR SOMBRE WHOLELLEY

One faint eternal eventide of gems. This cave was once an egg of rock within a vast magmatic flow. It crystallised inside, leaching rare and tainted carbons from the ultradense surge. Every compassed space is built from semiprecious stones. Amethyst, carnelian, agate. Glowing and flashing in dark bands like starfields seen by shadowed astronauts. Sharp with a vague-nebulae glow and shaping the darkness like the buzzing of a wasp shapes silence in an empty room.

GRAVATIC TWIST

At some point in its history gravity in this cave has been other than it is now. All the symptoms of erosion, water flow and calcite seepage are tilted 90 degrees from the way you expect. Speleothems grow across the cave from the walls, not up and down. Water cuts channels and leaves flowstone in the side not the floor. It was like this for a long time. There is no sign when it will change again.

HOKUSAI WAVE CAVE

This cave is mirrored in three dimensions to create a negative space. Like Hokusai's Wave when you turn the picture upside down. If you enter through a field of stalagmites reaching twenty feet, then at the other end will be and identical mirror-reversed field of stalactites hanging twenty feet. The cave mirrors in as many axis as you can comfortably manage.

If you turn it upside down there is another wave made of the empty space, but you probably knew that

SUMMERHAND CAVE

In summer you can place your hand flat over your open eye. The light seeps through your skin and lights your flesh inside. The glowing red-black-red of sunlight through your hand is the colour of this cave. Of the rock. Not bright enough to light the space, but present, like the phosphorescence at the centre of gems.

TV-SCREEN-DEEP

The colour of an old television screen just after it shuts down. Deep, deep inside: a tiny inverse you-shape staring back. The surface is staticky with fuzzy tangible electromagnetism like rubbed balloons and old technology. Impenetrable to magical sight, either way. May burn with moving black and white grains when someone tries to see through.

PSEUDOLITH

A built room carefully disguised to look exactly like a natural cave. The walls are plaster over brick or worked stone. The Speleothems are columns carved like natural forms. The organic wanderings are carefully designed. This could be the disguised watch-room for an Undercity long lost, a piece of weird decadent art, a dead Drow's folly, a deliberate magical act, forgotten training-place or careful temple. Possible secret doors. Possible ambush.

HAIR BRAID CAVE

An ancient lava bed makes up one surface. Twists of ropey rock make a roof like a giant rasta's dreadlocks. Thick knots of fresh-looking organic-seeming basalt interweaving but flowing one way. Good way to climb if its the wall. Nightmare if its the floor.