A Delaware judge yesterday blocked Consolidated Gold Fields PLC from buying additional shares in Newmont Mining Corp., but said the order did not affect 15.6 million shares of Newmont purchased by the British company in a "market sweep" Tuesday.

The judge's decision was a Pyrrhic victory for corporate raider T. Boone Pickens Jr., who is leading a rival effort to buy Newmont. Pickens had asked the court to stop Consolidated's buying spree in order to give Newmont shareholders an opportunity to consider a takeover offer from Ivanhoe Partners, an investment group led by Pickens. Analysts said Consolidated bought enough stock in a flurry of open market purchases Tuesday to effectively block Ivanhoe's takeover attempt.

At Ivanhoe's request, the judge scheduled a hearing Friday to reconsider whether to rule Consolidated's purchases of Newmont stock invalid. Stock traders have said, however, that it would be very difficult to undo the huge number of open-market purchases made by Consolidated.

Pickens and his associates could not be reached for comment yesterday.

Ivanhoe has alleged that the huge purchases by Consolidated, as well as a related agreement between Consolidated and Newmont, constitute a "lockout scheme" designed to unfairly prevent Newmont stockholders from taking advantage of a $72-a-share takeover bid by Ivanhoe.

Consolidated, which had owned 26.2 percent of Newmont, said in a Securities and Exchange Commission filing yesterday that it bought an additional 191,000 Newmont shares Monday and 15.6 million shares Tuesday to raise its stake to 49.7 percent. At that level, analysts said, it would be all but impossible for Ivanhoe's bid for control to succeed.

Ivanhoe is offering $72 a share for 28 million shares of Newmont's 66.8 million shares of stock. The partnership already owns 6.6 million shares, a 9.9 percent stake.

In blocking Consolidated from further purchases of Newmont, Vice Chancellor Jack B. Jacobs of the Delaware Chancery Court ruled that the agreement with Consolidated -- which allowed the British company to buy up to 49.9 percent of Newmont -- and other defensive measures taken by Newmont were "draconian." The judge said Consolidated's stock purchases would lock up control of the Newmont board for five to 10 years.

The judge issued a temporary order against further purchases and set a date of Oct. 1 for a hearing on a preliminary injunction in the case. The case is being heard in Delaware because that is Newmont's state of incorporation.

In another development yesterday, Newmont adopted still another takeover defense. It said that if it is the subject of an unwanted takeover in which a hostile suitor owning 50 percent or more of the company buys the remaining shares for less than was paid in earlier purchases, the shareholders would get cash from Newmont to make up the difference. Such an arrangement could deplete Newmont's cash coffers in a hostile takeover and make such a deal much less attractive.

Earlier this week, in addition to the agreement with Consolidated, Newmont took another step to block a takeover by Pickens by issuing a special $33-a-share dividend to shareholders in an effort to make the Ivanhoe Partners offer less attractive.