Ore Identification

Part of Metalworking

Before you can smelt metal, you must find it. Ore identification is the foundational skill that separates productive metalworking from wasted effort — knowing where to look, what to look for, and how to confirm what you have found.

Why Ore Identification Matters

In a rebuilding scenario, you cannot order metal stock from a supplier. Every nail, blade, and hinge must come from ore you find, process, and smelt yourself. Misidentifying ore means wasting days of fuel gathering and furnace-building on worthless rock. Correct identification, on the other hand, lets you target the easiest-to-smelt ores first and build a reliable metal supply chain.

The good news: humans identified and smelted ores for thousands of years before modern geology existed. The methods are visual, tactile, and chemical — all achievable with zero technology beyond fire and a few common materials.

Types of Metal Ore

Iron Ores

Iron is the most critical metal for rebuilding civilization. It is abundant and makes the hardest tools.

Ore Type	Appearance	Where Found	Smelting Difficulty
Bog iron	Reddish-brown crumbly nodules	Swamps, bogs, stream beds	Easy — lowest temperature
Hematite	Steel-gray to red-brown, heavy	Hillsides, exposed rock faces	Moderate
Magnetite	Black, very heavy, magnetic	Mountain regions, dark sand beaches	Hard — highest temperature
Limonite	Yellow-brown, earthy, crumbly	Near springs, wet areas	Moderate
Siderite	Gray-brown, crystalline	Sedimentary rock layers	Moderate — releases CO2

Start with Bog Iron

Bog iron is the easiest iron ore to find and smelt. It forms naturally in swamps and bogs where iron-rich groundwater meets oxygen. It requires the lowest smelting temperatures (around 1,100-1,200C) and was the primary iron source for Viking-age smiths.

Copper Ores

Copper was the first metal smelted by humans and remains valuable for electrical work, alloys, and corrosion-resistant vessels.

Ore Type	Appearance	Where Found	Notes
Native copper	Reddish metal chunks	Near volcanic areas, lakeshores	No smelting needed — just melt and cast
Malachite	Bright green, banded	Near copper deposits, often surface	Smelts easily at ~1,100C
Azurite	Deep blue, crystalline	Same locations as malachite	Often found alongside malachite
Chalcopyrite	Brassy yellow, metallic	Underground veins	Harder to process — requires roasting

Tin Ores

Tin is essential for making bronze (copper-tin alloy) and for tin-plating iron to prevent rust.

Ore Type	Appearance	Where Found
Cassiterite	Black to brown, very heavy crystals	Stream gravels (alluvial), granite regions

Tin is Rare

Tin deposits are geographically limited. In a rebuilding scenario, tin may be the bottleneck for bronze production. Prioritize scavenging tin from old cans, solder, and pewter before searching for cassiterite.

Lead and Zinc Ores

Ore Type	Metal	Appearance	Where Found
Galena	Lead	Heavy, silver-gray, cubic crystals	Limestone regions
Sphalerite	Zinc	Yellow-brown to black, resinous	Often found with galena

Where to Look for Ore

Geological Indicators

Ore deposits are not random. They follow geological patterns you can learn to read:

1. Stream beds and river gravels — Heavy ore fragments wash downstream and concentrate in bends, behind boulders, and in gravel bars. Pan stream gravel like a gold prospector.
2. Exposed rock faces — Cliff faces, road cuts, landslide scars, and eroded hillsides reveal subsurface minerals.
3. Color anomalies — Reddish soil often indicates iron. Green staining means copper. Black sand on beaches suggests magnetite.
4. Springs and seeps — Iron-rich water leaves orange-brown deposits. These indicate iron ore upstream.
5. Vegetation patterns — Some plants concentrate metals and grow preferentially on mineral-rich soils. Stunted or discolored vegetation can indicate metal-rich ground.

Landscape Reading

Follow the Water

Water is your best prospecting tool. Walk upstream from iron-stained springs. Pan gravel from stream bends. Check where tributaries join — heavier mineral fragments settle where current slows.

Specific terrain types to investigate:

• Bogs and swamps — Bog iron accumulates just below the surface as reddish-brown nodules
• Volcanic regions — Native copper, magnetite, and sulfide ores
• Limestone areas — Lead (galena) and zinc (sphalerite)
• Granite regions — Tin (cassiterite), sometimes copper
• Sedimentary layers — Iron (hematite, siderite) in banded formations

Field Tests for Identification

You do not need a laboratory. These field tests use only materials available in a survival scenario.

The Streak Test

Scratch the mineral across an unglazed piece of pottery (the back of a tile or broken pot). The color of the powder streak is more reliable than the mineral’s surface color:

Mineral	Streak Color
Hematite	Cherry red to reddish-brown
Magnetite	Black
Limonite	Yellow-brown
Malachite	Light green
Galena	Lead-gray
Cassiterite	White to light brown

The Weight Test

Ore is almost always heavier than ordinary rock. Pick up a suspect stone and compare it to a similar-sized piece of regular rock. Metal ores feel noticeably heavier.

Relative densities (water = 1):

• Regular rock: 2.5-2.7
• Iron ores: 3.5-5.3
• Galena (lead): 7.4-7.6
• Cassiterite (tin): 6.8-7.1
• Native copper: 8.9

The Magnet Test

If you have any magnet (salvaged from speakers, hard drives, or motors), test dark heavy minerals. Magnetite is strongly magnetic. Some hematite is weakly magnetic. No other common ore responds to magnets.

The Acid Test

Vinegar (acetic acid) or lemon juice can help:

• Malachite fizzes gently in vinegar and turns the liquid green
• Calcite (limestone, not an ore) fizzes vigorously — helps you rule it out
• Siderite fizzes weakly in strong vinegar

The Fire Test

Heat a small sample in a hot charcoal fire:

• Bog iron turns magnetic after heating
• Malachite turns black, then produces small copper beads if heated with charcoal
• Galena melts relatively easily and produces a lead bead

Lead Fumes

Never inhale fumes from heating galena or any suspected lead ore. Lead vapor is toxic. Always test in well-ventilated areas and stand upwind.

Processing Raw Ore

Sorting and Grading

Once you have collected ore, sort it by type and quality:

1. Visual sort — Remove obviously non-ore rock
2. Weight sort — In water, heavier ore sinks faster than lighter waste rock
3. Crush and wash — Break ore into walnut-sized pieces, wash in running water to separate lighter gangue (waste mineral)

Roasting

Some ores benefit from roasting before smelting:

1. Build a large wood fire
2. Stack ore on top in a single layer
3. Burn for 4-8 hours, let cool slowly
4. Roasted ore crumbles more easily and drives off sulfur and moisture

Roast Sulfide Ores

Chalcopyrite and other sulfide ores must be roasted before smelting to drive off sulfur. Without roasting, the sulfur contaminates the metal and makes it brittle and unusable. Roast in open air — the sulfur burns off as sulfur dioxide gas. Stand well upwind.

Crushing

Crush roasted or raw ore to increase surface area for smelting:

1. Use a large flat rock as an anvil
2. Break ore with a heavy hammer stone
3. Target pieces the size of gravel (5-15mm)
4. Do not over-crush to powder — fine dust blows out of the furnace

Building an Ore Inventory

Systematic Prospecting

Do not wander randomly. Survey your territory systematically:

1. Map water sources — Follow every stream, noting color changes and deposits
2. Check exposed geology — Walk cliff faces, road cuts, quarry walls
3. Sample widely — Collect fist-sized samples from every unusual-looking rock
4. Test at base camp — Run streak, weight, magnet, and fire tests on all samples
5. Mark locations — Create a map of confirmed ore sources with estimated quantity

Storage and Labeling

Keep tested ore samples organized:

• Store different ore types separately
• Mark each pile with the source location
• Note the test results (streak color, weight, magnetic response)
• Estimate the quantity available at each source
• Prioritize sources closest to your settlement and fuel supply

Common Mistakes

1. Confusing iron-stained rock with iron ore — Reddish color alone does not mean ore. Iron staining can color worthless sandstone. Always do the weight and streak test.
2. Ignoring bog iron — Many people search for dramatic rock formations when the easiest iron is literally underfoot in swampy ground.
3. Collecting too little ore — Smelting is fuel-intensive. A single bloomery run needs 20-50 kg of ore to produce a few kilograms of iron. Collect far more than you think you need.
4. Skipping the roasting step — Wet or sulfide-containing ores perform poorly in the furnace. A day of roasting saves days of failed smelts.
5. Testing in poor light — Streak tests and color assessments are unreliable in dim conditions. Always test in full daylight.

Summary

Ore Identification — At a Glance

• Start with bog iron (swamps, stream beds) — it is the easiest to find and smelt
• Use streak, weight, magnet, and fire tests to confirm ore identity
• Copper ores (malachite, azurite) are identified by green and blue coloring
• Follow water upstream from iron-stained springs to find ore sources
• Crush ore to gravel size and roast sulfide ores before smelting
• Collect and test systematically — map every confirmed deposit in your territory