晶体惯态，又称晶体习性，结晶习性，简称晶习，指矿物晶体趋向于某一种特定外形的特性。这种外形可以指单晶，也可以指晶簇的形态。晶体惯态主要取决于晶体本性，但有时也与生长条件有关。

在矿物学中，矿物晶体按发育程度分为按应有形状发育完整的自形晶，发育不完整但带有部分晶面的半自形晶和受限而未发育出应有晶面的它形晶。晶体惯态能帮助矿物学家识别大量的矿物，但特殊条件下形成的非常见晶形有时也会对判断造成误导。

影响晶体惯态的因素还包括生长过程中存在的微量杂质，孪晶和生长条件（如热，压力，空间），断层或冰川运动运动造成的条纹，多种晶形的组合等。属于相同晶系的矿物不一定表现出相同的晶体惯态。在特定地区发现的一些矿物具有独一无二的晶体惯态：例如，虽然大多数蓝宝石形成拉长的酒桶状状晶体，而在蒙大拿州发现厚板状的蓝宝石晶体。通常情况下，后者为红宝石的晶体惯态。蓝宝石和红宝石都是刚玉，由α-氧化铝掺杂不同属离子杂质形成。

In mineralogy, crystal habit is the characteristic external shape of an individual crystal or crystal group. A single crystal's habit is a description of its general shape and its crystallographic forms, plus how well developed each are. Recognizing the habit may help in identifying a mineral. When the faces are well-developed due to uncrowded growth a crystal is called euhedral, one with partially developed faces is subhedral, and one with undeveloped crystal faces is called anhedral. The long axis of a euhedral quartz crystal typically has a six-sided prismatic habit with parallel opposite faces. Aggregates can be formed of individual crystals with euhedral to anhedral grains. The arrangement of crystals within the aggregate can be characteristic of certain minerals. For example, minerals used for asbestos insulation often grow in a fibrous habit, a mass of very fine fibers.