Cavers in Mexico confront extreme conditions and find extraordinary
By Neil Shea
National Geographic Staff
Crystal Palace Photo Gallery at:
In a nearly empty cantina in a dark desert town, the short, drunk
man makes his pitch. Beside him on the billiards table sits a chunk
of rock the size of home plate. Dozens of purple and white crystals
push up from it like shards of glass. “Yours for $300,” he says. “No?
One hundred. A steal!” The three or four other patrons glance past
their beers, thinking it over: Should they offer their crystals too?
Rock dust on the green felt, cowboy ballads on the jukebox. Above the
bar, a sign reads, “Happy Hour: 8 a.m. to 9 p.m.”
This remote part of northern Mexico, an hour or so south of
Chihuahua, is famous for crystals, and paychecks at the local lead
and silver mine, where almost everyone works, are meager enough to
inspire a black market. “Thirty dollars.” He leans in. “Ten.” It’s
hard to take him seriously. Earlier in the day, in a cave deep below
the bar, I crawled among the world’s largest crystals, a forest of
them, broad and thick, some more than 30 feet long and half a million
years old. So clear, so luminous, they seemed extraterrestrial. They
make the chunk on the pool table seem dull as a paperweight.
Nothing compares with the giants found in Cueva de los Cristales, or
Cave of Crystals. The limestone cavern and its glittering beams were
discovered in 2000 by a pair of brothers drilling nearly a thousand
feet below ground in the Naica mine, one of Mexico’s most productive,
yielding tons of lead and silver each year. The brothers were
astonished by their find, but it was not without precedent. The
geologic processes that create lead and silver also provide raw
materials for crystals, and at Naica, miners had hammered into
chambers of impressive, though much smaller, crystals before. But as
news spread of the massive crystals’ discovery, the question
confronting scientists became: How did they grow so big?
It takes 20 minutes to get to the cave entrance by van through a
winding mine shaft. A screen drops from the van’s ceiling and Michael
Jackson videos play, a feature designed to entertain visitors as they
descend into darkness and heat. In many caves and mines the
temperature remains constant and cool, but the Naica mine gets hotter
with depth because it lies above an intrusion of magma about a mile
below the surface. Within the cave itself, the temperature leaps to
112 degrees Fahrenheit with 90 to 100 percent humidityhot enough that
each visit carries the risk of heatstroke. By the time we reach the
entrance, everyone glistens with sweat.
Preparing to enter the cave is like gearing up for a space walk. I
pull on a vest with more than a dozen palm-size ice packs sewn into
pockets across the chest and back. Then another vest to insulate the
ice against the heat. Then, over everything, a bright orange caving
suit. A helmet, a headlamp, a respirator mask blowing ice-cooled air.
Gloves, boots. Even for cavers cocooned in all this protective gear,
the heat is exhausting and dangerous; most trips inside last no more
than 20 minutes. Giovanni Badino, a physicist from the Italian
exploration group La Venta, leads us in.
Fallen obelisks, pillars of light, the crystals are enormous, some
several feet thick. On the floor and walls are clumps of smaller
crystals, sharp as blades and flawlessly transparent. Badino proceeds
slowly, careful not to damage the crystals, which are made of
selenite, a form of the common mineral gypsum. Selenite is
translucent and soft, easily scratched by boot heels, even
fingernails. Despite the ice suits, the heat and humidity are
oppressive. I remove the mask for a moment and suck in wet, hot air.
My lungs want to refuse it. There is a damp, heavy scent of earth and
an absolute stillness. Miserable conditions for humans, a perfect
nursery for crystals.
In their architecture crystals embody law and order, stacks of
molecules assembled according to rigid rules. But crystals also
reflect their environment. Spanish crystallographer Juan Manuel
Garc-Ruiz was one of the first to study the Naica crystals beginning
in 2001. More familiar with microscopic crystals, Garc was dizzied by
the proportions of the Naica giants. By examining bubbles of liquid
trapped inside the crystals, Garc and his colleagues pieced together
the story of the crystals’ growth. For hundreds of thousands of
years, groundwater saturated with calcium sulfate filtered through
the many caves at Naica, warmed by heat from the magma below. As the
magma cooled, water temperature inside the cave eventually stabilized
at about 136F. At this temperature minerals in the water began
converting to selenite, molecules of which were laid down like tiny
bricks to form crystals. In other caves under the mountain, the
temperature fluctuated or the environment was somehow disturbed,
resulting in different and smaller crystals. But inside the Cave of
Crystals, conditions remained unchanged for millennia. Above ground,
volcanoes exploded and ice sheets pulverized the continents. Human
generations came and went. Below, enwombed in silence and near
complete stasis, the crystals steadily grew. Only around 1985, when
miners using massive pumps lowered the water table and unknowingly
drained the cave, did the process of accretion stop.
In the presence of such beauty and strangeness, people cast around
for familiar metaphors. Staring at the crystals, Garc decided the
cavern reminded him of a cathedral; he called it the Sistine Chapel
of crystals. In both cathedrals and crystals there’s a sense of
permanence and tranquillity that transcends the buzz of surface life.
In both there is the suggestion of worlds beyond us.
Now, in the cave, a team of scientists and explorers is conducting
research and working on a documentary. Stein-Erik Lauritzen, a
professor of geology at the University of Bergen in Norway, is
retrieving samples for uranium-thorium dating. His preliminary
research suggests the largest of the crystals are about 600,000 years
old. Penelope Boston, an associate professor of cave and karst
science at New Mexico Tech, searches for microbes that might live
among the crystals. In some of them, tiny bubbles of suspended
fluidthe kind Garc studiedsparkle in our lights. They are little time
capsules: Italian scientists led by Anna Maria Mercuri extracted
pollen that may have been trapped within these inclusions. The grains
appear to be 30,000 years old and suggest that this part of Mexico
was once covered not by desert but by forest.
One long, slender beam bears a deep scar from where someone tried to
cut through it. I imagine a miner dripping and alone in the
smothering silence, his weak headlamp bouncing with each saw stroke.
Collectors might pay tens of thousands of dollars for a crystal from
this cave. Whoever he was, he quit before he could sever the crystal,
and mine owners later installed a heavy steel door to deter looters.
So far it has worked, but who knows if it will last. Miners, after
all, have access to drills and explosives. And while mining and
construction projects can be halted to save archaeological relics,
minerals in Mexico have no such protection.
The crystals could also be threatened by the lack of water. When the
cave was filled, water helped support and preserve the beams. Now,
with the cave empty and open to air, they may over time bend or crack
under their own weight and become dull, as gases such as carbon
dioxide wash in. The director of the mine told me his company, Peles,
is dedicated to preserving them, but the company’s main interest
isn’t crystals, and the basic activities of miningblasting, trucks
stirring up dustthreaten the gallery. Badino and others hope to
convince the company to do more (lobbying for UNESCO World Heritage
status has been mentioned), but so far the crystals exist in limbo,
probably more famous outside Mexico than within.
We stop for a moment to rest. Everything around us glitters; it is
as though we are standing inside a star. Badino turns, and the lines
crease at the corners of his eyes. He pulls his mask away. “You
know,” he says, smiling, “there would be worse places to die.”
Cathedral, star, tomb. We look for something to anchor the
otherworldly in the familiar. After half an hour we depart, soaked in
sweat, our veins throbbing, and a visiting filmmaker asks what it was
like. I have a little trouble. He nods, understanding.
“Es como un sue de ni,” he says. “It is like a child’s dream.”