Graham Donaldson, described previously by Scotgold as a "real enthusiast" for the project at Cononish, now has nearly 15.8 million shares with a paper value of £83,600.
The pair had declared a holding of 3.43% last month.
Mr Donaldson has been building his holding in the company, which is listed on the Australian Stock Exchange and the junior Alternative Investment Market in the UK, over the last couple of years.
The Donaldsons are Scotgold's largest investors ahead of chief executive Chris Sangster with a 2.91% holding, according to Reuters data.
In November Scotgold announced it is scaling back its planned Cononish gold mine to focus initially on extracting higher grade deposits after a fall in the price of the precious metal made it more difficult to raise development finance.
Scotgold has indicated it is now likely to seek £10 million in capital to start production at the mine near Tyndrum. This is down from the £25m originally proposed