
According to Quark, that's enough Latinum for 100 bricks or so. That tiny amount is supposed to fill 100 bricks of this:

That's quite a lot of gold for such a small amount of latinum. While the exchange rate from bars to bricks is unknown, what is known is the size of a single bar of Latinum, measured at 4.75 x 0.5 x 2.25 inches[1]. If we assume that the amount of latinum in that bar is minuscule compared with the amount we know goes into 100 bricks, we can simply assume that the weight of a bar is only that of the gold. Gold has a density of 19.3 g/cm3[2], or 0.697 lbs/in3. Since the volume of the bar is known to be 5.34375 in3, the total weight of a bar of latinum is 3.726 lbs each.
May not sound like much, but when you consider Quark tried to evacuate with 600 bars of Latinum[3], that means his case contained 2,235.6 lbs (over a ton) of gold. Unless Quark had an anti-grav unit, I don't think he's picking up a literal ton of gold. So if it's not that kind of gold, what is it? Well, a search of some common gold alloys yields information about other types of gold. A rich yellow gold alloy has 9 carats (9 parts out of 24, or 37.5%[4]) with the other 62.5% made up of silver and copper (31.25% each)[5]. Silver has a density of 10.49 g/cm3[6] (0.379 lbs/in3) and copper has a density of 8.94 g/cm3[7] (0.323 lbs/in3). If a bar were made of this alloy, it would weigh in at 2.569 lbs each. That's still 1,541.4 lbs in Quark's case during the evacuation.
We know that anti-grav units don't work on DS9[8] so how could Quark move that much Latinum around? Either the bars are of a super light metal plated with gold, are a very light weight gold alloy, or there's something else going on. No matter how you look at it, Latinum has to be the most inconvenient medium of trade. Having to move that much mass around must play hell with a ship's on-board ballast and inertial compensators. For small purchases it might not be that bad but for major purchases (such as one million bars of Latinum) it must be a major problem moving that much at any given time.