THERE IS a certain cheap postcard of the Mexican volcano Popocatepetl, printed by !Colleciones Tarjetas Postales!, that radiates power like a ikon. The photograph was taken from the air, some time around dawn. The sky fluoresces, jade; the peak's rusty cone soars in the cold light, topped with a skullcap of ice. There is nothing alive in the picture, not a stick, a tussock of grass. The landscape is drastic, desolate; its colors speak of rare earths, alchemical salts. You can almost believe, as the Aztecs did, that gods live in that high, smoking crater.

Popocatepetl, its summit 17,887 feet above sea level, is one of three great Mexican volcanos; the others are Citlaltepetl, highest at 18,700 feet, and Ixtacihuatl, 17,343. These are grand, gigantic mountains: In contrast, the highest peak in the Colorado Rockies is 14,433-foot Mount Elbert, while California's Mt. Whitney tops the Sierra Nevada at 14,495. In all of North America, only Alaska's Denali and Canada's Mount Logan are taller than Citlaltepetl.

A few hours from the United States by air, Mexico's tres picos offer Norteamericano climbers and trekkers an inexpensive and accessible alternative to the Himalayas, the Andes and the Alps. If you are a fanatical mountaineer, there is a good two weeks' worth of ice and rock on Popo, Ixty and Citlaltepetl; on the other hand, you can easily fit a visit to one of the peaks into a standard Mexican tour, as a counterpoint to the usual tropical beaches, Indian markets and languid rivers.

Popocatepetl (the name means "Smoking Mountain") is about 90 minutes from downtown Mexico City, via hired car; the fare, one way, is about $50, not bad if you split it up among several passengers. If you don't mind spending a few extra hours, you can take a train or bus to the town of Amecameca, and a local taxi from there; total cost, about $25. All prices quoted were in effect before the recent peso devaluation and may have been substantially reduced. The road ends at Tlamacas, at the upper edge of a fog-shrouded forest, where the Mexican government has built an imposing chalet, with dormitory and restaurant.

From Tlamacas, the most popular route up Popo follows a trail along the northern slopes of the peak, and then turns east, up a very steep, very long, and fiendishly exhausting slope of lava rubble, to the crater rim. It is close to a vertical mile, and there is usually snow on the upper portions of the route, enough to make ice ax and crampons advisable. There is a hut partway up the mountain, on the ridgeline called Las Cruces, but I would not advise using it: It is so badly vandalized, and strewn with trash, that it is best avoided. Most climbers climb from Tlamacas to the crater rim and back in a single, very long day, leaving at 3 or 4 a.m., by flashlight or headlamp, and coming back in the late afternoon. That is one cruncher of a slog, particularly if you have just come from a sea-level area like Washington; a few days of acclimatization, in Mexico City and at Tlamacas, would not be a bad idea.

Further advice: Carry sunglasses, a good parka and a large canteen of purified water. A small camp stove, for melting snow, may also come in handy. Keep a sharp eye on the weather: There have been dozens of fatalities on Popo, and all but a few have been caused by the storms that pounce with little warning, cutting visibility to nil and turning easy gravel screes into hazardous glare ice ramps. Winter is the best mountaineering season, weather-wise. La Casa del Excursionista, at Felix Cuevas 832-A, Colonia del Valle, is probably the best climbing shop in Mexico City. The proprietor speaks excellent English and can arrange for guided climbing on any of the volcanos. Panini's, at Avenue de Insurgentes Sur No. 2343, is also good.

The first officially recorded ascent of Popocatepetl was by the Englishmen Glennie and Taylor in 1827, but the local Indians surely made it to the summit long before that; they are powerful, sinewy little people, perfectly adapted to high altitude. For several decades, there was a sulphur-mining operation in Popo's crater, using local Indian labor.

One retired miner--you see him around Tlamacas from time to time, stooped, ancient, face black and cuneiformed from nearly a century of mountain sun--once climbed the mountain twice in one day. He climbed to the crater rim from his village to collect his pay, and descended all the way to the base of the peak before noticing that his pay voucher had not been signed. He turned, re-climbed those interminable slopes of lava and snow, got his voucher signed, and came back down again just as night fell. It's a great story, and it may even be true.

Popocatepetl is a primal, elemental sort of place, a realm of black cinder dunes, goblin gardens of basalt, sulphur-stained icicles hanging like tusks from ancient ice fields. Weird, compelling terrain. The Fire has been here, not so long ago; now it is the time of Ice, but the Fire will be back, you can sense it. It is at once ghastly and beautiful. I first traveled to Popo in 1974, and came within 500 feet of the summit before being driven off by foul weather; this last summer I returned, to give it another try. I am not sure I won't go back again some day; in fact, I probably shall. It is that kind of place.

This last trip, I backpacked 60-odd pounds of tent, sleeping bag, food and gear up past Las Cruces hut, and set up camp on a narrow ledge high on the peak's northwest side. For several days, I was almost completely alone: Occasionally, a mountaineer or two passed, summitbound, or a raven (Mexican edition of Corvus corax) yawped and flapped in the mists. The weather was fierce: It snowed, sleeted, hailed; the wind whipsawed the mountainside at gale force, with bits of rock and ice in its teeth. Every couple of hours, a loose rock bounded down the mountain and through my camp. Beautiful, empty time; the sunsets and dawns were striped with fire, the most intense I have ever seen.

The fifth morning, at 6 a.m., I started up from my campsite, armed with an ice ax and a canteen full of lemonade. When the sun rose, an hour later, I was already high on the summit cone, clambering up steep gullies of loose rock and dust. The view below was immense: a sea of thunderheads, blooming red and black, with the distant spike of Citlaltepetl on the eastern horizon, and Ixtacihuatl looming to the north. The slopes seemed to steepen as I approached the summit; the last hour took me across uncomfortably severe expanses of scree and snow. There was no real danger, but if you did fall, it was a good 3,000 vertical feet before you would stop.

By 10, I was at the summit, staring down into the caldera of Popo, 600-foot cliffs, clouds, smoke, a whiff of brimstone. I spent only five or 10 minutes up there; already the clouds were climbing the mountain, bringing the first storms of the day. It took me just 25 minutes to descend to camp, where I collapsed, utterly winded. Visibility was down to 40 or 50 feet, a thick, dank fog that smelled of stone. I had a skull-cracking headache, but otherwise I felt wonderful.

I have never climbed Ixtacihuatl, "The Sleeping Woman"; it is a grim-looking cluster of crags and glaciers, about 10 miles north of Popo across a high, forested saddle. It is supposed to be a more difficult ascent, from a technical standpoint; climbers should bring ice ax, crampons, rope, possibly even ice screws and snow stakes. The Mexican Guide School, at Reforma No. 76, Desp. 1707, Mexico City, can provide more information.

Citlaltepetl, or "Star Mountain," lies 100 miles to the east of Popo and Ixty, close by the Gulf of Mexico. You take an express bus from Mexico City to the classic Spanish colonial city of Puebla; from there, one or two smaller, slower local buses take you to Tlachichuca, a primitive hill town where Indians in serapes drive mules down the mud streets. From Tlachichuca, you have to hire a jeep to take you up to the hut at Piedra Grande; the jeep drivers charge about 50 U.S. dollars to drop you off at the hut and pick you up two or three days later. The rough ride up to Piedra Grande passes through pine forests, scattered fields of maize, and villages whose people have that peculiarly delicate mountain Indian look, a rare, birdlike beauty. Adobe shanties, riprap walls, tatters of cloud drifting over wet roofs; kerosene-lit rooms where rows of silent men slug down shots of raw mescal: this is the Old Mexico, earthen, harsh, powerful.

The shelter at Piedra Grande, 14,400 feet above sea level, is as lovely as the hut on Popocatepetl is wretched, a real first-class Alps-style shelter, with wooden tiers for sleeping. The standard route to the summit leads straight up the mountainside from the hut, over steep moraine debris and a long, long glacier. I must confess I have never been to the summit: The one time I was there, a terrific wind storm was sweeping the mountain, and I turned back on the lower verges of the glacier. My friend Gordon Wiltsie made it all the way to the crater rim that day, crawling on his hands and knees at the top to keep from being blown over. He had short mountaineering skis lashed to his pack, and part-way down he put them on and carved a tight run down to the moraine. Excellent skiing, he said later, but a bit dicey: If you fell, that was it, a header to the rocks, no second chance.

That night, there was a party at the Piedra Grande. Two Mexican climbers, well-to-do businessmen from Monterrey, had brought two cases of Carta Blanca beer and several bottles of tequila and brandy up the mountain; they were in a celebratory mood, having nearly made it to the summit that day, and they proceeded to drink, with the cooperation of the other occupants of the hut, every drop in every bottle. There were a couple of other Mexican climbers there, as I remember, and some Japanese, and a French group--the usual polyglot group you find on the volcanos.

The Mexicans from Monterrey told us that two Europeans had perished on the mountain just a month or two before, plummeting into a crevasse near the summit, never to be seen again. The Japanese were headed for Alaska in a couple of days, to do more climbing there. A portable radio wheezed mariachi music and static. The hut was full of warmth, talk, and laughter. Outside the door, it was moonlit and cold; the peak was sheathed in silver light. It was hard to imagine being anywhere else on earth.