Zero tax on $39375 in long-term capital-gains is correct if the total taxable income is $39375.
However, bullion ETF's based on physical bullion owe a collectibles long-term capital-gain tax rate of 28% except that a foreign ETF based on physical bullion might be classified as a PFIC and then filing a Form 8621 avoids the collectibles capital-gain rate.
Or bullion ETF's based on futures avoid the collectibles capital-gain rate. Bullion ETN's avoid the collectibles capital-gain rate.