ASX mining stock Iluka Resources Ltd (ASX: ILU) is trading 1.38% higher on Tuesday at $5.13 per share.

But if we take a long-term view, the critical minerals miner is notably down in 2024.

The Iluka Resources share price has tumbled almost 23% in the year to date.

Its sector peers have also fallen over this period, but not as much, with the S&P/ASX 200 Materials Index (ASX: XMJ) down around 15% over the same time frame.

By contrast, the benchmark S&P/ASX 200 Index (ASX: XJO) has risen 9% since the start of the year.

Considering all of this, it's interesting to note that three company directors at Iluka have just invested more of their own money into the business they run.

This may indicate that the directors feel Iluka Resources shares are trading at an attractive valuation.

The transactions occurred on 11 December when Iluka shares traded between $5.06 per share and $5.26 per share.

Let's check out the details.

ASX mining stock attracts further investment from directors

Iluka's Acting Chair, Andrea Sutton purchased 10,000 Iluka Resources shares last week.

The on-market transaction cost Sutton $48,901 and increased her holdings in Iluka by 45%.

She now holds 32,000 Iluka shares.

It's been more than three years since Sutton last traded Iluka Resources shares.

Sutton is sitting in for retiring chair Rob Cole.

Iluka announced Cole's retirement this week.

A final director's interest notice reveals that Cole left the company with 37,000 Iluka shares to his name, held via a family trust and a superannuation fund.

He had not traded any Iluka shares since late 2022.

Independent non-executive Director Lynne Saint purchased 7,365 shares on-market for $36,765.

Saint now holds 27,102 Iluka shares.

Independent non-executive director Peter Smith bought 10,141 Iluka Resources shares on-market for $50,981.

This is Smith's first trade since becoming a director in June. He purchased the stock through his self-managed superannuation fund.

These three trades this month follow a transaction in late November by Iluka Resources managing director and CEO Thomas O'Leary.

O'Leary picked up 236,744 performance rights under the company's long-term incentive plan.

The rights were approved by shareholders at the annual general meeting.

What does Goldman Sachs think of Iluka Resources shares?

As my colleague James reported last week, a new note from Goldman Sachs reveals the broker has retained its buy rating and 12-month share price target of $7.70 on Iluka shares.

This implies a potential upside of 50%.

The note followed an update from Iluka regarding funding for its Eneabba Rare Earth refinery in Western Australia.