Origins of Chalcocite Defined by Copper Isotope Values
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Bibliographic record
Abstract
The origin of chalcocite is explored through a comparison of the copper isotope values of this mineral from supergene enrichment, sedimentary copper/red bed, and high-temperature hypogene mineralization around the world. Data from the literature and the data presented here <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mo stretchy="false">(</mml:mo><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn fontstyle="italic">361</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math> reveal that chalcocite from high-temperature mineralization has the tightest cluster of values of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>δ</mml:mi><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">C</mml:mi><mml:mi mathvariant="normal">u</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn fontstyle="italic">65</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo>=</mml:mo><mml:mn fontstyle="italic">0</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">0.6</mml:mn></mml:math> in comparison to sedimentary copper/red bed <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mi>δ</mml:mi><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">C</mml:mi><mml:mi mathvariant="normal">u</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn fontstyle="italic">65</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo>=</mml:mo><mml:mo>-</mml:mo><mml:mn fontstyle="italic">0.9</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">1.0</mml:mn></mml:math> and supergene enrichment <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mi>δ</mml:mi><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">C</mml:mi><mml:mi mathvariant="normal">u</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn fontstyle="italic">65</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo>=</mml:mo><mml:mo>+</mml:mo><mml:mn fontstyle="italic">1.9</mml:mn><mml:mo>±</mml:mo><mml:mn fontstyle="italic">1.8</mml:mn></mml:math>. Although the errors of the means overlap, large portions of the data lie in different values, allowing for distinguishing ranges for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mi>δ</mml:mi><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">C</mml:mi><mml:mi mathvariant="normal">u</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn fontstyle="italic">65</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> of <−1<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mrow><mml:mtext>‰</mml:mtext></mml:mrow></mml:math> for sedimentary copper/red bed, between <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M7"><mml:mo>-</mml:mo><mml:mn fontstyle="italic">1</mml:mn></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M8"><mml:mo>+</mml:mo><mml:mn fontstyle="italic">1</mml:mn></mml:math> for high-temperature hypogene, and >+1 for supergene enrichment chalcocite. The copper isotope values of sedimentary copper/red bed and supergene enrichment chalcocite are caused by redox reactions associated with the dissolution and transport of copper, whereas the tighter range of copper isotope values for hypogene minerals is associated with processes active with equilibrium conditions.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it