Gold plummeted to $635.50 an ounce in New York yesterday, a drop of more than $30 from Friday, and dealers attributed the loss to a statement by Treasury Secretary G. William Miller reiterating conditions for new sales of U.S gold. The dollar rose against all major currencies.

Miller said U.S. gold might be sold if it were priced attractively, and if the Treasury wished to reduced borrowing in the capital markets, to counteract speculation in gold or other commodities, or to smooth out disequilibrium in the U.S. balance of payments.

In Zurich gold closed at $645.50, down $22 from Friday's close of $667.50. In London an ounce of gold sold for $644.50 at the close, down from $669.50.

In New York, gold fell to $635.50 an ounce from Friday's $662.25. The Comex settlement price was $633 an ounce, down from $665.50 Friday.

Silver also was weaker, closing at $15.775 an ounce, down from $16.405 Friday.

The dollar gained a bit in Europe and held steady in New York, where dealers said trading was very quiet.

In London the pound eased to $2.3760 from Friday's $2.3780 and was trading at $2.3768 in New York.

In Tokyo the dollar rose to 218.25 yem fron Friday's 217.70.