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To measure density, geologists use a balance to first determine the precise mass of a mineral sample. Then they plac the mineral in water to determine how much water the sample displaces. The volume of the displaced water equals the volume of the sample. Density : Mass/Volume

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Each mineral has a characteristic density. Recal that density is the mass in a given space, or mass per unit volume. No matter how large or small the mineral sample is, the density of that mineral always remain the same.

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Some minerals can be indentified by special physical properties. Calcite bends light to produce double images . Other minerals conduct electricy, glow when placed under ultraviolet light, or are magnetic

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Crystals

Crystals have amazed us throughout history. For example, the crystal structure of a diamond reflects light in such a way to mesmerize even the harshest critic. But what is a crystal? The term crystal is used to convey different meanings at the microscopic or macroscopic level.

At the microscopic level, a crystal is a solid formed by regularly-repeating patterns of molecules that are connected together. Now, not all solids are crystals. In a non-crystal solid, the arrangement of the molecules is random throughout the material; it's not regular. Still, at the microscopic level, the crystal is characterized by the unit cell, which is a collection of molecules repeated in exactly the same arrangement throughout the entire material.

At the macroscopic level, geologists use the term crystal shape, or crystal habit, to refer to the visible external shape of a sample of a material. The shape or habit results from the common or characteristic shape of either a single crystal or aggregate of crystals. In this lesson, we will discuss two general types of crystal habits. The first exists as regular polygons and are thus termed euhedral, where 'eu' means true. The second type doesn't exist in regular geometric forms.

Euhedral Crystals

Let's look first at the euhedral crystals. Euhedral crystals have flat surfaces, or facets, with sharp angles. This is rare in nature, as most crystals don't form with sharp edges and smooth flat facets.

For example, diamonds have an octahedral habit as they have eight facets, 'octa' meaning eight. Magnetite is another mineral with an octahedral habit. As the name suggests, this mineral is magnetic. Ancient humans discovered the property of magnetism through this mineral.

Garnets are most commonly dodecahedrons as they are 12-sided. Many gemstones are garnet minerals and some are quite valuable rubies. Some minerals form a cubic, or a cube-shaped habit, such as halite, galena, and pyrite. Halite is nothing more than common rock salt, galena is the natural mineral form of lead, and pyrite, or iron pyrite, is also known as fool's gold, as it has a shiny metallic luster much like gold.

It is important to note that while most minerals have one common crystal habit or crystal shape, some can form different habits depending on the conditions in which they are formed.

Non-Geometrical Crystals

Now let's move on to the crystal habits that don't have a regular geometric shape. Some minerals rarely develop perfect geometric forms at the surface. However, other characteristics can be helpful in identification of these minerals. For example, kyanite has a bladed habit, as its crystals are elongated and flattened in one direction, much like the blade of a knife.

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crystal shape of minerals: forms and types - video & lesson transcript | study.com

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Crystal Shape of Minerals: Forms and Types - Video & Lesson Transcript | Study.com

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Crystals have amazed us throughout history. For example, the crystal structure of a diamond reflects light in such a way to mesmerize even the harshest critic. But what is a crystal? The term crystal is used to convey different meanings at the microscopic or macroscopic level.

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Luster is the term used to describe how light is reflected from a mineral's surface.

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Less common minerals are not found evenly throughout the crust. Instead, several processes can concentrate these minerals, o bring them together, in deposits. An ore is a deposit of valuable minerals contained in rocks.
These ores are mined and the iron or lead is separated from the rock

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The streak of a mineral is the color of its powder. However, the streak color and the mineral color are often different.

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Some elements occur in nature in pure form, and not as part of a compound. Elements such as copper, silver, and gold are also minerals. Almost all pure, solid elements are metals.

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Each mineral has characteristic propertiesthat can be used to identify it.

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many minerals form from magma and lava.

MInerals from as hot magma cools inside a crust , or as lava hardness on the surface. When these liquids cool to a solid state, they form crystals.

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A mineral that splits easily along flat surfaces has the property called cleavage. The way atoms are arranged in micaallows to slit easily in one.  Fracture describes how a mineral looks whn it breaks apart in an irregular way.

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Almost all minerals are compounds. In a compound, 2 or more elements are combined  so that the elements no longer have distinct properties. 

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Almost all minerals are compounds. In a compound, 2 or more elements are combined  so that the elements no longer have distinct properties. 

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Sometimes the elements and compounds that from minerals can be dissolved in water o from solutions.
A SOLUTION is a mixture in which one substance is dissolved in another

When elements and compounds that are dissolved in water leave

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The Mohs harness scale is used to rank the hardness a ranking from 1 to 10 hardness can be determine by a scratch test. A mineral can scratch any mineral softer than itself, but can be scrathed by any mineral that is harder

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Every mineral always contains certain elements in defintie proportions. An element is a substance composed of a single kind of atom.
Quartz always contains 1 atom of silicon for every 2 atoms of oxigen.

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Every mineral must be able to form from materials that were not part of a living thing. But, Coal comes only from living things(The remains of plants that lived thousands of years ago).

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A mineral is a naturally occuring solid that can form by inorganix processes and that has a crystal structure and a definite quemical composition. For a substance to be a mineral it must have all 5 of these characteristics, so it´s a quartz or a coal mineral. 

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A mineral is a naturally occuring solid that can form by inorganix processes and that has a crystal structure and a definite quemical composition. For a substance to be a mineral it must have all 5 of these characteristics, so it´s a quartz or a coal mineral. 

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A mineral´s particles line up in a pattern that repeats over and over again. This repeating pattern forms a solid called crystal.
A crystal has flat sides, called faces that met at sharp edges and corners.
While Quartz has a crystal structure , most coal lacks a crystal structure.

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A mineral is always solid and has a definite volume and shape. Both Coal and Quartz are solids

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Quartz forms naturally as magma cools and hardens benath Earth´s surface.
Coal forms naturally from the remains of plants that are squeezed tighly together.