Why are some crystals large and perfect, while others are small and irregular?
The only answer in my book that seems close is :
The crystal shape, hardness, cleavage and density of a mineral are determined by the internal arrangement of its atoms or ions.
I don't see anything about why it would be small or large just that they have 6 basic shapes.
time and space grown is also a factor
The size and shape of crystals can be influenced by a variety of factors, including the conditions under which they form. While the internal arrangement of atoms or ions does determine the crystal shape, it does not directly explain why some crystals are large and perfect while others are small and irregular.
The size of a crystal is primarily influenced by the rate of crystal growth. If a crystal has sufficient time and space to grow without any external hindrances, it can continue to deposit layers of atoms or ions onto its surface, resulting in a larger crystal. On the other hand, if growth is impeded by factors such as limited space or a rapid rate of cooling, the crystal may not be able to grow to a larger size.
The perfection or imperfection of a crystal refers to the degree of regularity in its arrangement and the presence of defects. Perfect crystals have a highly ordered atomic structure with minimal imperfections, while imperfect crystals may contain impurities, dislocations, or irregularities in their arrangement.
Factors that can contribute to the formation of large and perfect crystals include:
1. Slow cooling: When a hot and molten material cools slowly, it provides more time for atoms or ions to arrange themselves in an orderly manner, promoting the growth of larger and more perfectly formed crystals.
2. Abundance of building blocks: If there is an abundant supply of the necessary atoms or ions available for crystal growth, it increases the likelihood of larger crystals forming.
3. Low impurity levels: Crystals tend to grow better in environments with fewer impurities. High levels of impurities can interrupt the regular growth of crystals and lead to imperfections.
4. Controlled growth conditions: In some cases, crystals can be grown in controlled laboratory environments, where factors such as temperature, pressure, and concentration are carefully controlled to optimize the growth process. This can result in the formation of larger, more perfect crystals.
In contrast, factors that can lead to small and irregular crystals include:
1. Rapid cooling: If the cooling process happens too quickly, it does not allow enough time for atoms or ions to arrange themselves in an orderly manner, resulting in smaller and less perfect crystals.
2. Limited space for growth: Crystals that form in confined spaces, such as within rocks or in tight crevices, may have restricted growth opportunities, leading to smaller and irregularly shaped crystals.
3. High impurity levels: Presence of impurities can disrupt the growth process and result in distorted or imperfect crystal formation.
It's important to note that while these factors provide general explanations, there can be exceptions and variations depending on the specific mineral and the conditions under which it forms.