QQQ has huge tech exposure, but it is not a 'tech fund' in the pure sense either. The fund's arcane weighting rules further distance it from anything close to plain vanilla large-cap or pure-play tech coverage.
During the time when Earth was forming and was in a molten state, heavy materials like iron and nickel sank to the center of the Earth's mass and lighter materials floated to the surface of the mass. The very center of what we call the core, is solid in the middle because of the increased pressure in that region.
The core's heat is mostly due to the slow decay of radioactive elements left over from when the planet first formed. The molten iron outer core lies about 3000 kilometers below our feet, while the solid iron inner core is another 2000 kilometers further down. A few other elements, including oxygen and silicon, are thrown in for good measure. But for the most part, iron rules the Earth's underbelly.