Abarim Publications' online Biblical Hebrew Dictionary
Dictionaries commonly lists two separate roots חרץ (haras), which may very well be one and the same:
The verb חרץ (haras 1) means to cut, carve or divide, and with a rare notable exception (Leviticus 22:22) is mostly used in the mental sense of being sharp of mind or discerning, or to cut into an issue and determine (Job 14:5, Isaiah 10:22-23, Daniel 9:26-27), act decisively (2 Samuel 5:24, Isaiah 28:22) or decide one way or the other (1 Kings 20:40, Daniel 11:36). From this verb derive (and the following may overlap somewhat):
- The adjective חרוץ (harus 1), meaning sharp or separating, literally of a threshing device (Isaiah 28:27, Amos 1:3), or in the mental sense: decisive or diligent (Proverbs 13:4). "The hand of the diligent makes rich" (Proverbs 10:4) and "will rule" (Proverbs 12:24). "The precious possession of a man is diligence" (Proverbs 12:27), "and the plans of the diligent lead surely to advantage" (Proverbs 21:5). Note that this adjective meaning diligent is identical to three other words, including חרוץ (harus 4) meaning gold (see below).
- Noun חרוץ (harus 2), meaning decision or separation or something to that extent. It occurs only once, in the harrowing cry: "Multitudes, multitudes in the valley of decision!" (Joel 3:14).
- Identical noun חרוץ (harus 3), now apparently meaning moat or division (and only in the enigmatic: "it will be built again, with plaza and moat", Daniel 9:25).
- The noun חריץ (haris), meaning a sharp cutting tool (2 Samuel 12:31) or a thing cut (1 Samuel 17:18).
- The plural noun חרצנים (harsannim) of unclear meaning, apparently to do with bits or pieces of a vine (Numbers 6:4 only).
The second root חרץ (haras 2) doesn't appear to be used as verb in the Bible, but occurs all over the Semitic language spectrum with variations of the meaning of to be yellow (or to be a sun-flower). But from it derives the important noun חרוץ (harus 4), which is a secondary word for gold. The regular word for gold is זהב (zahab), whereas the noun פז (paz) appears to denote gold leaf. How our noun חרוץ (harus) differs from זהב (zahab) isn't clear, but technically it simply means "the yellow stuff" (likewise, in most Indo-European languages, the word for gold relates to the word for yellow as both tend to stem from the Proto-Indo-European root "ghel-", meaning to shine).
How a verb that means to be yellow (or gold) came to be identical to a verb that means to discern or divide isn't clear either, but since red is the first color babies learn to see (hence words like rude and rudimentary, and probably even names like Adam, Edom and Red Sea), and yellow the second, the color yellow is ingrained in human consciousness as the color of multifariousness, multiple options and thus initial uncertainty and doubt but when experience yields confidence, discernment and decisiveness. A complete color vision is marked by seeing the color blue, which explains why in many cultures, blue is associated with royalty, divinity and maturity.
Gold was appreciated in the ancient world because it doesn't react with anything (gold doesn't rust), which meant that gold could be combined with precious stones or worked to very fine detail, without a risk of losing elements of the composition due to material degradation. Moreover, information carved, cast or molded into gold would virtually last forever. Hence gold, and particularly fine crafted gold artifacts came to signify human understanding of perpetual natural law — hence the enigmatic "I advise you to buy from Me gold refined by fire so that you may become rich" (Revelation 3:18), which probably has little to do with the actual gold trade and rather parallels the proverb "The hand of the diligent makes rich" (Proverbs 10:4; see above).
Whatever the technical pedigree of these words, the noun חרוץ (harus), meaning gold, is identical to the adjective חרוץ (harus) meaning diligent, and the noun חרוץ (harus) meaning diligence and decisiveness. That suggests that our noun probably refers to fine crafted gold artifacts rather than the mere material or bars or plain rings and such. The city of Tyre was apparently known for its fine gold artifacts (and note the striking similarity between Zechariah 9:3 "gold like mire" and Job 41:30: "threshing sledge on mire"). In Psalm 68:13 our word is applied to the pinions of a dove. In Proverbs 3:14, 8:10, 8:19 and 16:16 the gain of wisdom is declared higher than that of gold.