ऊषरकर्बुरः पक्वलोष्ठवर्णो वा त्रपुधातुः ॥ कZ_०२.१२.१४ ॥
ūṣarakarburaḥ pakvaloṣṭhavarṇo vā trapudhātuḥ
Tin ore/metal is mottled like saline/alkaline soil (ūṣara-karbura), or of the color of a ripe clod (pakva-loṣṭha).
They translate technical mineral recognition into common visual references so non-specialist officials can apply them in the field.