Stats
Actions
Tags
From agent-almanac
Identifies minerals and ores in the field using hardness, streak, luster, cleavage, crystal habit, and chemical tests. Useful for prospecting and geological observation.
How this skill is triggered — by the user, by Claude, or both
Slash command
/agent-almanac:mineral-identificationThis skill is limited to the following tools:
The summary Claude sees in its skill listing — used to decide when to auto-load this skill
Identify minerals in the field using physical properties, systematic elimination, and simple field tests.
Identify minerals in the field using physical properties, systematic elimination, and simple field tests.
Before handling, observe the specimen in context.
Field Context:
+--------------------+------------------------------------------+
| Observation | Record |
+--------------------+------------------------------------------+
| Host rock | What type of rock is it in/on? |
| | (granite, basite, sandstone, schist...) |
+--------------------+------------------------------------------+
| Geological setting | Vein, disseminated, massive, placer, |
| | weathering surface, cave deposit |
+--------------------+------------------------------------------+
| Associated | What other minerals are nearby? |
| minerals | (quartz veins often host gold; iron |
| | staining suggests oxidation zone) |
+--------------------+------------------------------------------+
| Crystal form | Visible crystals? Habit? Size? |
| (if visible) | (cubic, prismatic, tabular, massive) |
+--------------------+------------------------------------------+
Expected: Field context recorded before handling the specimen.
On failure: If geological context is unclear (loose specimen, urban find), proceed with physical properties only — context would have helped narrow candidates but is not strictly required.
Apply the diagnostic tests systematically.
Diagnostic Property Tests:
LUSTER (how it reflects light):
- Metallic: reflects like metal (pyrite, galena, gold)
- Vitreous: glassy (quartz, feldspar)
- Pearly: like a pearl (muscovite, talc surfaces)
- Silky: like silk fibers (asbestos, satin spar gypsum)
- Earthy/dull: no reflection (kaolin, limonite)
- Adamantine: brilliant, diamond-like (diamond, zircon)
HARDNESS (Mohs scale — scratch test):
+------+-----------+----------------------------------+
| Mohs | Reference | Can Be Scratched By |
+------+-----------+----------------------------------+
| 1 | Talc | Fingernail |
| 2 | Gypsum | Fingernail (barely) |
| 3 | Calcite | Copper coin |
| 4 | Fluorite | Steel nail (easily) |
| 5 | Apatite | Steel nail (just) |
| 6 | Feldspar | Steel nail cannot scratch |
| 7 | Quartz | Scratches glass |
| 8 | Topaz | Scratches quartz |
| 9 | Corundum | Scratches topaz |
| 10 | Diamond | Scratches everything |
+------+-----------+----------------------------------+
Test: try to scratch the specimen with each reference tool,
starting from soft to hard. The hardness is between the tool
that fails and the tool that succeeds.
STREAK (powder colour on porcelain):
- Drag the specimen firmly across an unglazed porcelain tile
- Record the colour of the powder line
- Streak colour is often different from specimen colour
- Critical: hematite is grey-black but streaks RED
- Critical: pyrite is gold but streaks BLACK
- Minerals harder than the streak plate (~7) will not leave a streak
CLEAVAGE AND FRACTURE:
- Cleavage: breaks along flat planes (mica: 1 direction, feldspar: 2)
- Fracture: breaks irregularly (conchoidal = curved like glass, uneven, fibrous)
- Note number of cleavage directions and angles between them
SPECIFIC GRAVITY (heft test):
- Hold the specimen and assess: does it feel heavier or lighter
than expected for its size?
- Heavy: possible metallic ore (galena, gold, magnetite)
- Light: possible pumice, sulfur, or organic material
Expected: A profile of the specimen: luster, hardness range, streak colour, cleavage/fracture type, and relative density.
On failure: If a property is ambiguous (e.g., luster between metallic and vitreous — "sub-metallic"), record both options. Ambiguity reduces confidence but does not prevent identification.
Additional tests for specific mineral groups.
Special Field Tests:
MAGNETISM:
- Hold a magnet near the specimen
- Strong attraction: magnetite (or possibly pyrrhotite)
- Weak attraction: some iron-bearing minerals
ACID TEST (10% HCl):
- Drop acid on the specimen surface
- Vigorous fizzing: calcite (CaCO3)
- Fizzing on powder only: dolomite (scratch surface first, then apply acid)
- No fizzing: not a carbonate
TASTE (only for suspected halite):
- Salty taste: halite (NaCl)
- Do NOT taste unknown minerals generally — some are toxic
SMELL:
- Sulfur: rotten egg smell (sulfides when scratched)
- Clay: earthy "petrichor" smell when breathed on (clay minerals)
TENACITY:
- Brittle: shatters when struck (most silicates)
- Malleable: deforms without breaking (gold, copper, silver)
- Flexible: bends and stays (chlorite, some micas)
- Elastic: bends and springs back (muscovite mica)
Expected: Additional diagnostic data that narrows the identification further.
On failure: If special tests are unavailable (no magnet, no acid), proceed with the basic properties — they are sufficient for most common minerals.
Cross-reference the property profile against known minerals.
Common Mineral Identification Key (simplified):
METALLIC LUSTER:
- Black streak + hard (6+) + cubic crystals = PYRITE
- Black streak + soft (2.5) + heavy + cubic = GALENA
- Red-brown streak + hard (5-6) + heavy = HEMATITE
- Yellow streak + soft (1.5-2.5) + yellow = GOLD (if malleable)
or CHALCOPYRITE (if brittle, harder, green-black streak)
- Black streak + magnetic = MAGNETITE
NON-METALLIC, LIGHT-COLORED:
- Vitreous + hard (7) + conchoidal fracture = QUARTZ
- Vitreous + hard (6) + 2 cleavage planes = FELDSPAR
- Vitreous + soft (3) + fizzes in acid = CALCITE
- Pearly + very soft (1) + greasy feel = TALC
- Vitreous + soft (2) + 1 perfect cleavage = GYPSUM
NON-METALLIC, DARK-COLORED:
- Vitreous + hard (5-6) + 2 cleavage at ~90 degrees = PYROXENE
- Vitreous + hard (5-6) + 2 cleavage at ~60/120 degrees = AMPHIBOLE
- Vitreous + soft (2.5-3) + 1 perfect cleavage + flexible = BIOTITE (mica)
Expected: A mineral identification or a shortlist of 2-3 candidates with the distinguishing test needed to differentiate them.
On failure: If the specimen does not match any common mineral, it may be a rock (aggregate of minerals) rather than a single mineral, or it may require laboratory analysis (thin section, XRD).
gold-washing — alluvial gold recovery uses mineral identification skills to read stream deposits and assess gold-bearing gravelsnpx claudepluginhub pjt222/agent-almanacIdentifies gemstones using optical properties, physical tests, and inclusion analysis. Useful for unknown specimens, verifying seller claims, and distinguishing natural stones from simulants.
Analyzes materials with pymatgen: crystal structures, phase diagrams, electronic structure, surfaces, interfaces, Materials Project API. Handles structure conversion, symmetry analysis, VASP/Gaussian/QE output.
Plans geological field surveys with objectives, mapping scale, sampling strategy, and data collection methods for structural geology, stratigraphy, or mineral exploration.