It's a coin that was minted at the New Orleans Mint. That facility operated from 1838 to 1861 and then again from 1879 to 1909.
To find out the value of a specific coin minted there you'll need to post a new question with its date.
26.73 grams.
The "O" mint mark is from New Orleans
As of 4/12 a 1898 O Morgan silver dollar in MS-65 condition is worth $238.
Please look at the coin again and post new question. With the date of 1839 it can't be a Morgan dollar. The Morgan dollar was first issued in 1878.
The Morgan silver dollar is a collectors item and can be about $39
The 1901 Morgan with no mintmark is worth more than the one with the "O" mintmark, but the difference depends on the condition (grade) of the coins. A 1901-O Morgan in the grade of EF-40 has an average value of $29.00 A 1901 Philadelphia (no mintmark) Morgan in the same grade is $105.00.
An 1879 "Silver Dollar" is a Morgan dollar.
The 1881-O (New Orleans) Morgan is common, retail values are $17.00-$26.00 for circulated examples.
The O is the mint mark, it stands for the New Orleans mint.
The 1885-O Morgan dollar is common, in general values are $32.00-$38.00 depending on grade.
A Morgan dollar IS a silver dollar. The term Morgan refers to the designer George T. Morgan who created the images used from 1878 to 1904 and in 1921.
Please look at the coin again. The first Morgan was struck in 1878. A silver dollar dated 1869 would be a Liberty Seated dollar and none were struck at the New Orleans Mint.