Mineral Identification and Properties

Comprehensive vocabulary flashcards covering the Mohs Hardness Scale, specific gravity values, diagnostic characteristics, and distinguishing properties of key minerals.

Specific Gravity (SG)

A measure of a mineral's density compared to water, indicating how heavy it feels, calculated by comparing the mass of a mineral to the mass of an equal volume of water.

Streak Test

A mineral identification test performed by rubbing a mineral on a porcelain plate to reveal its true color in powdered form.

Crystal System

A structural classification (such as cubic, monoclinic, or trigonal/hexagonal) that provides insight into a mineral's internal structure and growth patterns.

Talc

The softest mineral with a Mohs hardness of $1$, an SG of $2.58\text{--}2.83$, a white streak, a light green, white, or gray color, a waxy feel, and a monoclinic crystal system; used in talcum powder.

Gypsum

A soft, transparent mineral with a Mohs hardness of $2$ that can be scratched with a fingernail (hardness $2.5$); occurs in varieties such as alabaster and selenite.

Calcite

A mineral with a Mohs hardness of $3$, which shares the exact same hardness value as a copper penny.

Fluorite

A halide mineral with a Mohs hardness of $4$, an SG of $3.1\text{--}3.3$, a white streak, and a cubic or dipyramidal structure; harder than calcite and used in gemstones and industrial applications.

Apatite

A phosphate mineral with a Mohs hardness of $5$, an SG of $3.1\text{--}3.2$, a white streak, a trigonal/hexagonal crystal system, and various colors, especially green.

Feldspar

A common igneous rock-forming mineral with a Mohs hardness of $6$ (equal to window glass) featuring a salmon-pink color and a distinctive luster.

Quartz

A hard silicate mineral with a Mohs hardness of $7$, an SG of $2.65$, a colorless-white streak, no cleavage, and a trigonal/hexagonal crystal system; used in glass making and occurs as agate, amethyst, and jasper.

Topaz

A mineral with a Mohs hardness of $8$ that exhibits variable colors and typically forms well-formed prismatic crystals.

Corundum

An extremely hard mineral with a Mohs hardness of $9$ that displays reddish or purplish hues, forms small column-like opaque crystals, and yields rubies and sapphires.

Diamond

The hardest known mineral with a Mohs hardness of $10$, an SG of $3.52$, a cubic crystal system, a white streak, and an adamantine luster; used in jewelry and industrial cutting.

Galena

A heavy, lead-gray metallic mineral with an SG of $7.58$, perfect cubic cleavage, composed of lead sulfide, and serving as a major ore of lead.

Barite

A white non-metallic mineral with an SG of $4.5$, which is unusually heavy for a non-metallic mineral due to its barium content.

Gold

A valuable metal with a very high SG of $19.3$ that is smoother than pyrite, recognizable by its color, and typically forms nuggets.

Silver

A valuable metal with a high SG of $10.5$ characterized by a highly reflective metallic color that is usually tarnished.

Bauxite

An oxide mineral with a hardness of $1\text{--}3$, an SG of $2.3\text{--}2.7$, a white streak, and a yellow or brown color.

Celestite

A soft, translucent mineral that is typically white or blue, utilized for decorative purposes and crystal healing.

Chalcopyrite

A brassy yellow mineral of medium hardness that tarnishes to bright red, purple, yellow, and orange, often confused with gold and mined as an ore of copper.

Dolomite

A medium-hardness mineral featuring cream-colored platy crystals, sometimes embedded with dark specks; applied in construction and agriculture.

Epidote

A greenish-yellow, grainy mineral of medium hardness that can be confused with olivine; utilized as a gemstone and collector's item.

Graphite

A soft, shiny silver-colored mineral that leaves dark smudges and is used in pencil lead.

Halite

Commonly known as rock salt, identified by its cubic crystal shape and distinct odor.

Hematite

A mineral that can appear black, gray, or rusty red, recognized specifically for leaving a cherry red streak.

Hornblende

A black mineral characterized by short, stubby, and often striated crystals.

Kaolinite

A chalk-like mineral, usually colored white and orange, commonly utilized in ceramics.

Lepidolite

A pink or lilac-colored variety of mica that is frequently found in platy sheets.

Magnetite

A magnetic mineral that produces a gray or black streak and is frequently confused with hematite.

Malachite

A mineral that is consistently green with a green streak, frequently found alongside azurite.

Muscovite

A thin, platy mica mineral occurring in white, yellow, or tan shades.

Olivine

A light green or yellowish-green mineral whose transparent gem-quality specimens are known as peridot.

Opal

A mineral substance where precious varieties exhibit iridescence, while most common varieties are opaque white.

Pyrite

A brassy mineral known as fool's gold that forms cubic crystals and produces a distinctive blackish green streak.

Rhodonite

A mineral found in pink and red shades, typically occurring in massive habits.

Sodalite

A dark mottled mineral that is always blue, distinguishable from azurite.

Sphalerite

A mineral displaying a resinous luster and variable coloration, typically yellowish or reddish.

Staurolite

A mineral that characteristically forms short, brown prismatic crystals.

Sulfur

A distinctly yellow non-metallic mineral that emits a noticeable sulfurous odor when rubbed.

Tourmaline

A mineral of variable coloration that typically crystallizes as long prismatic crystals with vertical striations.

Tremolite

A light-colored mineral featuring small bladed crystals, historically utilized in the production of asbestos.

Ulexite

A white mineral that resembles a bundle of threads and exhibits natural fiber-optic light-transmitting capabilities.

Azurite

A mineral uniquely recognized by the fact that it is always blue, making color a defining identifier.