A colloidal mixture like the one you described, containing soil particles dispersed in water, is a heterogeneous mixture.
Some key points about heterogeneous vs homogeneous mixtures:
• Homogeneous mixtures have a uniform composition and phase. The components at any point in the mixture have the same properties. Examples include solutions, alloys, gases.
• Heterogeneous mixtures have a non-uniform composition or phase. The components can be distinctly visible or have different properties at different points in the mixture. Examples include colloids, suspensions, emulsions.
• In a colloid like the soil in water solution you described, the soil particles are suspended in the water but do not dissolve or fully integrate into the water. So it has two phases - soil particles and water. The properties and composition vary at different points.
• These soil particles can eventually settle down over time due to gravity, as you observed. But as long as the particles remain suspended, the solution remains a heterogeneous colloid.
• Other signs of a heterogeneous mixture: Properties vary in different parts of the mixture, phases can be seen separately, components can be filtered or centrifuged apart.
So in summary, based on your description, the cloudy soil-water solution is indeed a heterogeneous colloidal mixture, not homogeneous. Let me know if you need more details.