Minerals

Geologists are strict about the word mineral, and the Regents exam tests that. To count as a mineral, a substance has to pass five checks. It must occur naturally. It must be inorganic, meaning it was never alive. It must be a solid. It must have a definite chemical composition. And its atoms must be arranged in an orderly, repeating crystal structure. Miss any one of those and it is not a mineral, no matter how much it looks like rock.

That checklist leads to some surprises. Ice is a mineral. It is natural, inorganic, solid, made of H2O, and crystalline, as every snowflake shows. Coal is not a mineral, because it formed from plants that were once alive. Glass is not a mineral either, whether it is natural or manufactured, because its atoms are frozen in a disordered arrangement with no repeating pattern. Nothing man-made counts, which is why a lab-grown diamond is chemically a diamond but not technically a mineral.

How to Identify Minerals Using the Properties of Common Minerals Chart

Every useful property a mineral has comes from something you cannot see, which is how its atoms are arranged inside. The clearest proof is a pair of minerals made of exactly the same element. Graphite and diamond are both pure carbon. In graphite the carbon atoms bond in flat sheets that slide apart so easily the mineral smears onto paper, which is why it is used as pencil lead. In diamond the same atoms lock into a rigid three-dimensional framework, which makes it the hardest natural substance known. Same element, different structure, completely different properties.

This is also why color is the least reliable way to identify a mineral. Tiny impurities tint quartz white, pink, purple, gray, or black without changing what it is. The properties that matter, hardness, cleavage, streak, luster, and density, all trace back to the internal structure, which never changes. Identification means testing for the structure you cannot see.

Luster is the first question to ask, and it is the first split in the mineral identification flowchart. Does the surface reflect light like polished metal, or not? Metallic minerals such as galena and pyrite go down one branch. The glassy, pearly, and dull nonmetallic minerals go down the other.

Hardness is how well a mineral resists scratching, ranked 1 to 10 from talc to diamond. You test it by finding out what scratches what. A fingernail is about 2.5, a copper penny about 3.5, a steel nail or glass plate about 5.5, and an unglazed streak plate about 7. If a mineral scratches glass but quartz scratches it, the hardness is between 5.5 and 7. That sentence is a complete Regents answer.

Streak is the color of a mineral's powder. You find it by dragging the mineral across an unglazed tile. Surface color can fool you, but powder color does not. Pyrite looks like gold but leaves a greenish-black streak, and real gold never does.

Cleavage or fracture describes how a mineral breaks. If its internal bonds are weaker in some directions, it cleaves along flat planes. Mica peels into sheets, halite snaps into cubes, and feldspar breaks into right-angle steps. If the bonds are equally strong in every direction, the mineral fractures into rough or curved surfaces instead, like quartz and garnet.

Special tests settle the stubborn cases. Calcite fizzes in dilute acid. Magnetite jumps to a magnet. Graphite writes on paper. Halite tastes like the table salt it is, although the lab rule is firm and nobody licks the specimens.

A handful of minerals do most of the work of building Earth's crust, and almost all of them are silicates, built around silicon and oxygen. Feldspar is the most common mineral family in the crust. It makes up the blocky pink and white grains in granite. Quartz is hard and chemically tough, so it is left behind when everything around it weathers away. That is why so many beaches are quartz sand. The micas peel into glittering sheets. Outside the silicates, calcite builds whole landscapes of limestone and marble.

Then come the minerals people mine. Galena is heavy and silver, and it is the ore of lead. Magnetite is an iron ore you can identify with a magnet. Pyrite is called fool's gold because it has fooled so many people panning for gold. Garnet is hard and deep red, and it is New York's official state gemstone. It is mined in the Adirondacks at one of the oldest continuously operating mines in the country, mostly to be crushed into high-quality sandpaper.

A mystery specimen is on the table, and its appearance is already noted below. Run whichever tests you want, in any order, then identify it. Good geologists get there in as few tests as possible.

Pages 16 and 17 of your reference tables hold the Mineral Identification Flowchart, and it is open on your desk during the exam. Learn how it is laid out now. The chart splits first by luster, with metallic on top and nonmetallic below. Within each group it sorts by hardness. For every mineral it lists the hardness number, cleavage or fracture, common colors, distinguishing characteristics, composition, and everyday uses. The acid fizz, the magnetism, and the taste are all listed under distinguishing characteristics.

The exam uses this chart in both directions. Sometimes it gives you properties and asks for the mineral. Metallic luster, a green-black streak, and a hardness of about 6 walk you straight to pyrite. Sometimes it gives you the mineral and asks for a property, such as what calcite is used for, or which mineral in the chart is an ore of iron. Either way the habit is the same one the lab above builds. Start at the luster split, narrow by hardness, and let one distinguishing characteristic finish the job.

You have handled a dozen minerals today without noticing. There is graphite in your pencil, halite on your fries, and gypsum inside every wall of your school. Quartz is melted into your window glass, and it vibrates inside your phone to keep time. Talc goes into powders, and fluorite is where fluoride got its name. Winter road salt in this state comes from thick beds of halite deep under western New York, left behind by an ancient sea that evaporated more than 400 million years ago. Nearly everything manufactured starts as a mineral pulled out of rock, which is a good reason to know how to tell them apart.

• Mineral Identification Flowchart (pages 16 and 17). The whole chapter, in chart form. Practice both directions: properties to mineral, and mineral to property. Note the luster fork, the hardness column, and the distinguishing characteristics column where the special tests live.
• Mineral Composition of Igneous Rocks (page 14). The mineral composition bands of that chart are these same minerals: feldspar, quartz, mica, and their darker partners. This chapter is the vocabulary for the next one.

Download the current tables from NYSED (2026 Revised Edition, used from the 2026-27 school year): Reference Tables for Earth and Space Sciences.

• A mineral is naturally occurring, inorganic, solid, with a definite composition and a crystalline structure. Ice qualifies; coal and glass do not.
• Properties come from internal atomic arrangement, which is why graphite and diamond, both pure carbon, could not be more different.
• Color is the least reliable property. Identify with luster, hardness, streak, cleavage or fracture, and the special tests.
• Cleavage means breaking along flat planes of internal weakness; fracture means rough or curved breaks.
• Calcite fizzes in acid, magnetite grabs a magnet, pyrite's streak is greenish black, graphite writes.
• Most crustal minerals are silicates; feldspar is the most abundant, and garnet is New York's state gemstone.

Ten Regents-style questions, one at a time in a focused view, each with an instant explanation. The set reshuffles when you reach the end, so you can keep practicing as long as you like.