Final answer:
A mineral's crystal form is best developed when there is abundant space for it to grow unimpeded, allowing the atoms to arrange themselves in the crystal's natural lattice structure.
Step-by-step explanation:
A mineral's crystal form is typically best developed when there is ample space for the crystals to grow without any impediment. For a crystal to exhibit well-defined geometric shapes, which we refer to as its crystal form, it requires sufficient space for the unhindered arrangement of its constituent atoms into the natural lattice structure.
Unimpeded growth allows each mineral to grow steadily over time, and the atoms can arrange themselves in the most stable and energetically favorable geometric pattern. This is not directly related to the silicon and oxygen content, the type of bonding within the mineral, or whether the growth occurs in tight spaces; rather, it is about how freely the mineral can expand and form its crystal structure.