Touchstone and gold alloy needles
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Touchstone and needles
Touchstones are flinty, silicified, fine grained rocks. The name touchstone has reference to its use as a streak plate for gold. Needles of gold alloy of known composition were employed in assaying other alloys by comparing the marks made on the touchstone.
Details
- Category:
- Metallurgy
- Object Number:
- 1903-186
- type:
- touchstones and needles
- credit:
- Museum of Practical Geology
