ASSESSMENT AT LOCAL TAX RATE.

In any year in which at least 1,000 tons of iron ore concentrate is not produced from any 40-acre tract or governmental lot containing semitaconite, a tax may be assessed upon the semitaconite therein at the local tax rate prevailing in the taxing district and spread against the net tax capacity of the semitaconite; such net tax capacity shall not exceed the greater of: (a) the net tax capacity specifically assigned to the semitaconite material in said land in the assessment for the year 1958, or, (b) an amount sufficient to yield a tax of $1 per acre less the amount of any tax assessed against such land under the authority of section 298.26 .