Joni Mitchell has been talking for almost two hours now. The Geffen Records offices in Los Angeles have emptied, and the parking lot attendants are threatening to tow away her Mercedes.

But Mitchell shows no sign of winding down the conversation. Instead, she waltzes across the room for a cup of coffee and fires up yet another cigarette.

Mitchell is in the mood to chat about her life these days. She has a one-woman show of her paintings on display in Japan. Her latest album, Chalk Mark in a Rain Storm, is her best-received record of the decade. And her six-year marriage and artistic partnership with her coproducer and bassist, Larry Klein, has never been better.

"We work very, very well together," she says of Klein, whose contributions to the Chalk Mark album included taking the cover photo of his wife.

"After six years of marriage, a lot of the bugs are out of the relationship," she says. "He's a very thoughtful person, a patient person, a talented person. Being an only child and a self-sufficient artist for all this time, it's hard for me to give and let another person in. But he's very solid in himself. He provides me with a kind of music I don't make. And he loves working with me. I mean, we're partners at this point."

Too much togetherness hasn't smothered the romance?

"Oh, no. We're closer for having worked together. Because separation can rip a marriage apart. We're growing parallel at this time in our life. We're tighter than we were in the first few years of our marriage."

Emotional stability is relatively new for Mitchell, still best known for her frank accounts of romantic trials and triumphs in her Seventies albums Blue, For the Roses and Court and Spark. As she leans back in her chair, her black outfit and wide-brimmed hat framing her parchment skin and blond, board-straight hair, the frail, Canadian-born folk singer with the acoustic guitar and the sensitive soul is still apparent.

Recent photos of her tend to emphasize the wide arch of her mouth and her soaring cheekbones. But from across a desk, her face lit only by a lamp and the occasional flame from a cigarette lighter, her eyes dominate, large and liquid and resembling pale blue moons. Lines appear on her forty-four-year-old face only when she laughs - which is often.

In her straightforward manner and soft, lilting voice, she still conveys vulnerability, or, as she describes it, "a hickish quality."

But over her twenty-one-year recording career, Mitchell has acquired a resilient core, toughened by the wild fluctuations in her fortune and the radical changes in public perceptions of her. In the early Seventies, she was the preeminent female singer-poet of the Woodstock generation.

Her songs, many inspired by her rock-star boyfriends, articulated the confused dynamics of male-female relationships in the wake of the sexual revolution. To her fans, Mitchell was more than a performer: she was a therapist, a heroic confidante. The adoration made her uncomfortable, she says.

"At the time of Blue and the more self-confessional albums, I noticed people were worshiping me," Mitchell says with a laugh, slightly embarrassed at the notion. "I said, 'Whoops! What's happening here?' that's a terrible position to be in. I knew that the first time I showed any kind of humanness, I was going to come falling off of there. So I said, 'Let's get the humanness out there now.'"

So she showed her humanness and down she went - sooner than expected. When she recorded jazz albums in the mid to late Seventies, she was derided as a delettante.

In the Eighties, she has been pretty much ignored. Her first two post-jazz albums, Wild Things Run Fast and Dog Eat Dog, met with mixed critical reactions and public indifference.

"Part of the problem has been my timing," Mitchell says of those two records. "If either of those albums would have come out later, they would have been more palatable. If you get too far ahead of current events, I think you suffer. The climate in which things are released is very important."

With Chalk Mark, Mitchell seemed determined to make a contemporary album. She enlisted the contributions of several well-known pop musicians including Billy Idol, Peter Gabriel, Willie Nelson, and Wendy and Lisa. Is mass appeal important to her?

"I want to recoup my costs," she responds without hesitation. "These albums are expensive to record. But mass appeal? I like my mobility. I demand the right to walk around by myself. If you get too big, that becomes a source of embarrassment for other people. You know what I mean?"

But now it's almost 9 p.m., and Mitchell is finally running out of steam. Still, after the tape recorder is put away and good nights are exchanged, she recalls an incident that she feels summarizes her life:

Mitchell was performing in Canada as part of a benefit concert for the Cree Indians. Afterward, backstage, she walked into the dressing room to find a girl restrained by bodyguards. "The girl broke loose and screamed at me, 'There she is, the English whore. The English whore,' " Mitchell says. "Seconds later, an Indian boy came up to me and said: 'On behalf of my people, we thank you for coming. We think you are a saint.'"

And I thought, 'Isn't this strange? These two extreme reactions at the same time.' Now you would think that this would be enough of a life lesson that every compliment and every insult would roll off my back from that day on," she says, as if thinking aloud.

Was it?

She pauses a moment. "No," she says, exploding into laughter. "The whole thing was completely wasted on me."