GOLD AND ICE. Why do miners brave the harsh conditions of northern Canada? For 611 ounces of yellow metal a day -- worth $200,000

SHINING in the headlights of the jeep, the white crystals on the walls of the underground mine road glitter like a star-crowded sky. The crystals are not precious gems, however, but ice clinging to the purplish-black iron-sulfide ore -- which bears gold. Some 500 feet above, the surface temperature is minus 4 degrees F., mild by the winter standards of this area just south of the Arctic Circle. Deep in the mine it is not quite so cold. The air is warmed by the heavy equipment. Nonetheless, miners still wear heavy parkas and thermal jeans while they work. And salt is added to the drilling fluid to keep it from freezing.

The object of the effort under these harsh conditions? About 611 ounces of yellow metal per day -- worth a bit more than $200,000 (US) at current market prices.

Somehow, the mining operation seems improbable.

Here, 250 miles northeast of the town of Yellowknife in the Northwest Territories, Echo Bay Mines Ltd. used a C-130 Hercules cargo plane to fly in the material for the mine, the mill, the housing, and even recreation facilities. There were no roads. Gathering gold by the micron

The Lupin operation is the only major mining complex in the world to be completely flown onto the site, its executives claim.

Starting in 1980, it took 20 months and some 1,100 flights carrying loads of as much as 25 tons. Those loads included machinery, construction equipment, a ball mill for grinding the ore (specially designed to fit exactly into the Hercules), 2,200 tons of structural steel, enough cement for 9,500 yards of concrete, dishes, beds, food -- whatever was needed for employees.

The goal of this massive undertaking is to gather gold grains that rarely exceed 100 microns (1 micron = 1 millionth of a meter) in diameter. There is only enough of these gold grains in a ton of ore to add up to an average 0.325 ounces. Yet, perhaps surprisingly, this tiny percentage makes the Lupin mine one of the highest-grade gold mines in North America.

The ore must be blasted out of the frozen ground. In this barren land, the permafrost extends 1,770 feet below the surface, a situation that improves safety, since the frozen conditions mean the mine has no problems with flooding.

After blasting, the ore must be hauled to the surface, as much as 1,700 tons a day. There it is crushed, ground, preaerated, thickened, leached, precipitated, and eventually refined into gold bullion -- 195,137 ounces of it last year.

It costs $169 an ounce to retrieve gold from the Lupin mine. With the market price of gold around $340 an ounce, the mine makes a good profit. `Our strengths are Canadian'

``It is a pretty simple business,'' says Robert F. Calman, chairman of Echo Bay Mines. The process of extracting gold from its ore was developed some 100 years ago. But Mr. Calman and his employees still take pride in the efficiency and low cost of their mining and extracting operation, especially in the harsh conditions of Canada's far north.

``It required a lot of ingenuity to make it pay,'' the mine company executive recalls. ``Our strengths are peculiarly Canadian.''

Not the least of these strengths are the tough people who work in Lupin.

``The money is real good,'' says Ren'e Tourigny, a French-Canadian miner who has worked in Algeria and in other Canadian mines.

He says he doesn't mind the cold, especially when he compares it with the heat he had to put up with while sinking a shaft in Algeria. ``You adapt and dress for it,'' he says. ``It is easier to adapt for cold than mines that are real hot.''

Nor does he object to the long winter nights here, especially since a good part of his working life is spent underground in artificial light anyway. In summer, the almost perpetual light gives him a chance to fish for Arctic char and lake trout after his 12-hour shifts. `There's real good fishing.''

A measure of civilization has been brought to this frontier site. The employees live in a barrackslike residential complex with about 240 beds, most in two-bed rooms, with two rooms sharing a bathroom. Since one occupant in each room is generally on leave, the employees essentially have rooms to themselves.

Miners and surface employees both work two weeks, 12 hours a day, every day. Then they have two weeks off to rejoin their families, flying south on the company's Boeing 727 to Yellowknife or to Edmonton, Alberta, where the company is headquartered. (One young miner has been flying the two hours to Edmonton, thence to Honolulu, every two weeks to see a girlfriend.)

Mr. Tourigny likes the two-weeks-in, two-weeks-out routine on which the mine's shifts are operated. ``It gives you more time for your family than if you were working down south. It is a big advantage. You can do a lot of traveling. The thing that takes getting used to is being away from your family for two weeks.'' But he does enjoy his colleagues at the mine, describing them as ``a different breed of people.''

Altogether there are some 370 employees, of which about 170 are on the site at one time. A small number of these are women who work in the offices, the warehouse, or the kitchen, or as cleaning staff, and there are three female miners. About 10 percent of the employees are Inuit (Eskimos).

The kitchen, operated by a contractor, serves excellent food. Employees have voted to allow no alcohol on the site. The bags of those returning from leave are inspected to enforce the rule.

With overtime and bonuses, the operator of a Jumbo mining machine might make $50,400 a year. But that is the high end of the salary range.

Because of the extremities in weather (at its worst, 49 degrees below zero, plus a 50-knot wind kicking up ice crystals), all facilities are joined by covered walkways. When going outdoors in winter, an employee notes, ``people have to use common sense.'' An unprotected cheek or ear could quickly freeze. Satellite TV, real flowers

For the comfort and recreation of the workers, there are four satellite television channels, long-distance telephones, a full-time nurse, an outdoor ice hockey or broomball rink, weight-lifting facilities, a handball court, a sauna, a hot tub, a summer baseball field, and such touches as small bouquets of real flowers on the dining room tables.

On a mild winter day, an ambitious employee might take a power augur down to the nearby lake, drill through seven feet of ice, and fish for lake trout, pulling up the occasional 21-pounder.

Mine manager Robert Gilroy figures that operating a mine up here costs about one-third more than it would at Yellowknife, which is connected to Edmonton by a road. It would cost even more but for an unusual winter project -- construction of a 370-mile-long ``ice road'' to Yellowknife.

Each February since 1983, Echo Bay Mines has bulldozed a trail here to truck in as many supplies as possible for the entire year. Despite the distance, it is far cheaper than hauling them in by air.

The ice road stretches 40 miles along a gravel government road, 60 miles over treeless land, and the remaining 270 miles over deeply frozen lakes. The trucks travel in small convoys, a safety measure when subzero temperatures could quickly mean disaster for the driver of a truck that broke down. A couple of way stations are set up to provide fuel and minor maintenance for the trucks and a break in the 24-hour run for the drivers. A company helicopter also helps out when needed.

Driving across the ice, the convoys proceed at about 20 miles an hour until near the shore. Then the heavily laden trucks crawl along until on land. Otherwise, they set up a wave in the seven- to eight-foot-thick ice that could cause it to break up. As it is, the drivers don't usually wear their seat belts so they can jump quickly should the ice give way. So far, a truck axle has slipped through the ice a few times, but not a truck itself. Inventory kept by computer

The cost of preparing the road each year is about $1 million. But the 872 truckloads it carried last winter saved about $4 million, compared with the cost of bringing in the materials by air. The mine keeps 15,000 items on hand in its Lupin warehouse, with a computerized inventory system. The $22 million worth of supplies includes 4.6 million US gallons of fuel for a 12-megawatt, diesel-powered electric plant that roars away day and night.

Profits for Echo Bay Mines were down last year because of a drop in the average price for gold. But for the first quarter of this year, both gold prices and earnings were up handsomely.

Like other Canadian producers, the company is profiting in part from labor unrest in South Africa, a principal free-world competitor in the gold market, and in part from the rising popularity of Canada's Maple Leaf gold coin, as investors increasingly boycott the South African Krugerrand for political reasons.

Operating in an atmosphere of political and economic stability, Canadians have been opening new mines. By the early 1990s, Canadian gold production should reach some 7 percent of noncommunist production, up from 5.3 percent in 1980, an output of roughly 90 tons a year.