5,200,000 kg of quartz (silicon dioxide, a.k.a. rock) is about 4/5 the volume of an Olympic swimming pool, according to Wolfram Alpha; the same mass of iron is

5,200,000 kg of quartz (silicon dioxide, a.k.a. rock) is about 4/5 the volume of an Olympic swimming pool, according to Wolfram Alpha; the same mass of iron is about 1/3 of that. So whatever the actual composition of micrometeorites it is not a lot of material even on a human scale.