ferric ammonium oxalate

Amid the Iron Islands—perhaps non-ferric metals are scarce in the Seven Kingdoms?
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Nontraditional flavors ammonium nitrate, C-4, and gelignite did not test well.
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Ammonium nitrate is extremely common, and pretty dangerous, and also extremely useful.
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Crystals of urea nitrate or oxalate (Fig. 19) will soon appear and can be recognized with the microscope.
A Manual of Clinical Diagnosis|James Campbell Todd

Crystals of calcium oxalate are insoluble in acetic acid or caustic soda.
A Manual of Clinical Diagnosis|James Campbell Todd
The long axis of the hip-roof crystal is often so shortened that it resembles the envelop crystal of calcium oxalate.
A Manual of Clinical Diagnosis|James Campbell Todd
The sediment usually contains abundant amorphous phosphates and crystals of triple phosphate and ammonium urate.
A Manual of Clinical Diagnosis|James Campbell Todd
Characteristic octahedral crystals of calcium oxalate (Fig. 47) appear after ingestion of certain vegetables.
A Manual of Clinical Diagnosis|James Campbell Todd