While on Mount Sinai, God tells Moses to build a tabernacle and gives instruction on the important items that will reside within it. The golden lampstand is one of these items that is described in meticulous detail.
Exodus 25: 31-40 is the specific section dedicated to God's description of the lampstand:
31 “You shall make a lampstand of pure gold. The lampstand shall be made of hammered work: its base, its stem, its cups, its calyxes, and its flowers shall be of one piece with it. 32 And there shall be six branches going out of its sides, three branches of the lampstand out of one side of it and three branches of the lampstand out of the other side of it... continue
In Exodus 37:17-24 we read the description of the lampstand's construction by Bezatel and his craftsmen. This passage is almost an echo of God's command.
The term "pure gold" shows up in both of the passages. Rachel Hachili, author of The Menorah, the Ancient Seven-Armed Candelabrum: Origin, Form and Significance, writes that the specification of "pure gold" is only for the most sacred objects of the tabernacle because of its purity. Just "gold" is for other objects.
In Exodus 27:21 there is a description of a lamp that is continuously burnt in the tent of meeting before the veil of testimony. Aaron and his sons had the privledge and responsibility to care for this lamp.
In the tent of meeting, outside the veil that is before the testimony, Aaron and his sons shall tend it from evening to morning before the LORD. It shall be a statute forever to be observed throughout their generations by the people of Israel.
Again, in 2 Chronicles 13:11 there is a description of this eternally burning lamp.
They offer to the Lord every morning and every evening burnt offerings and incense of sweet spices, set out the showbread on the table of pure gold, and care for the golden lampstand that its lamps may burn every evening. For we keep the charge of the Lord our God, but you have forsaken him.
Yarden, L. The Tree of Light: A Study of the Menorah. London: Horovitz Publishing Co, 1971.
Hachlili, Rachel. The Menorah, The Ancient Seven-Armed Candelabrum: Origin, Form and Significance. Edited by John J. Collins. Boston: Brill, 2001.