If it has one, it's under the date. For this year, only proof coins have a mintmark.
If you are asking about a small (13mm) 1853 Liberty Head gold dollar, the mintmarks are on the reverse under the wreath.
Starting in 2009 the date & mintmark was moved to the edge of the coin, it's not gold and it's only a dollar.
The mint mark on a $5 gold coin from that era is on the reverse (tails) side, just below the eagle.
depending on condition, about $300
On the reverse just to the left of the arrows
The P is the mint mark for Philadelphia.
The price of gold in 2000 was 279.11. Gold is well over the thousand dollar mark in the present market.
Should be a d mark on back side left by arrow
mint mark is to the left of the value on the reverse.
A date is needed. Post new question.
With no mint mark or an "S", about $1000. That could go up to $1500 with a CC mint mark.
With no mint mark, around $1000 With a D or S mint mark, $1000 to $1500 depending on condition. has a g mark