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Hi there!
I found 8. I've listed them below:
Crystal Habit
If a mineral crystallizes without any impediments to its growth, it may assume a characteristic shape, or crystal habit which reflects its internal crystal structure (diagram: crystal habits). Some common crystal habits are illustrated in Figure 1-6. The term anhedral is used to describe minerals without well-formed crystal habits (which are vastly more common in rocks).
Luster
Luster refers to the way in which light is reflected from the surface of a mineral. The two basic classes are metallic luster, which describes the reflection of polished metal surfaces, and nonmetallic luster, which includes pearly, resinous, silky, vitreous (or glassy), and waxy lusters. Luster is best described from fresh and unweathered surfaces, and preferably from crystal faces. Weathered minerals are typically described as earthy in luster.
Hardness
The hardness of a mineral refers to its resistance to scratching. It is a measure of the strength of the bonds between the constituent atoms in a mineral: Minerals with relatively strong chemical bonds have greater resistance to scratching and are thus harder than minerals with relatively weak chemical bonds.
The relative hardness of a mineral is measured by the Mohs scale of hardness, which was developed by the German mineralogist Friedrich Mohs in the nineteenth century (Mohs hardness scale).
Cleavage
Cleavage describes the tendency of some minerals to break or split along flat surfaces called cleavage planes. Cleavage planes are surfaces of weak chemical bonds in mineral crystals. For example, the chemical bonds in muscovite, which has a sheet structure, are strong within the planes of the silicate sheets but weak between them. This causes muscovite crystals to cleave well into thin sheets which can be peeled away like layers of an onion.
Some minerals such as mica, feldspar, and fluorite have good to excellent cleavage in one, two, three, four, or even six different directions, and they cleave cleanly to form regular geometric shapes with smooth cleavage planes.
Fracture
Fractures are rough nonplanar breaks which cut randomly through mineral crystals. Minerals fracture rather than cleave whenever the bonds between their constituent atoms are equally strong in all directions, so that there are no preferred planes of weakness in their structures.
Fractures are very common to the framework silicates such as quartz, which exhibits distinct smooth, concentric, dish-shaped conchoidal fracture patterns. Other patterns include fibrous, which describes a wood-like splintery fracture, and uneven, which describes a rough and irregular fracture.
Color and Streak
The color of a mineral is one of its most obvious properties, but it is not always diagnostic. The color of a mineral can be greatly affected by trace amounts of chemical impurities. For example, quartz (SiO2) is light colored and transparent, but amethyst is a variety of quartz which is tinted purple by traces of iron.
Fortunately, there are many minerals (particularly the oxide, sulfide, native metal, and hydroxide minerals) which are not affected in this way and can be recognized on the basis of their colors. The best way to examine the color of such minerals is to grind them against a streak plate of unglazed porcelain and examine the color of the powder trace which the mineral leaves behind.
Specific Gravity
Specific gravity is defined as the ratio of the weight of a mineral to the weight of an equal volume of water. It is essentially a measure of the density of a mineral and thus reflects its chemical composition. The specific gravity of a mineral can be measured precisely in a laboratory, and it can be estimated by feeling the heft of the mineral.
Other Properties
There are several other properties which are diagnostic of specific minerals.
Effervescence describes the reactivity of minerals to dilute hydrochloric acid (HCl). This "acid test" is a diagnostic property of carbonate minerals such as calcite and dolomite.
Magnetism is attraction to magnets, steel paper cliips, and other similar objects. It is diagnostic of the mineral magnetite.
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