13.Fair Value Measurements

Financial assets and liabilities and nonfinancial assets and liabilities are measured at fair value on a recurring (annual) basis under a framework of a fair value hierarchy which prioritizes the inputs into valuation techniques used to measure fair value into three broad levels. This hierarchy gives the highest priority to quoted prices (unadjusted) in active markets and the lowest priority to unobservable inputs. Further, financial assets and liabilities should be classified by level in their entirety based upon the lowest level of input that was significant to the fair value measurement. The three levels of the fair value hierarchy per ASC 820 are as follows:

Level 1: Unadjusted quoted market prices in active markets for identical assets or liabilities that are accessible at the measurement date.

Level 2: Quoted prices in inactive markets for identical assets or liabilities, quoted prices for similar assets or liabilities in active markets, or other observable inputs either directly related to the asset or liability or derived principally from corroborated observable market data.

Level 3: Unobservable inputs due to the fact that there is little or no market activity. This entails using assumptions in models which estimate what market participants would use in pricing the asset or liability.

The Company has consistently applied the valuation techniques discussed in Notes 2, 10 and 15 in all periods presented.

Recurring Fair Value Measurements

The following table summarizes the Company’s financial assets and liabilities measured on a recurring basis at fair value at December 31, 2017 and 2016 by respective level of the fair value hierarchy:


	Level 1		Level 2		Level 3		Total
	(in thousands)
At December 31, 2017
Assets:
Cash and cash equivalents	$	3,250	$	—	$	—	$	3,250
Trade accounts receivable		314		—		—		314
Short-term investments		238		—		—		238
	$	3,802	$	—	$	—	$	3,802

At December 31, 2016
Assets:
Cash and cash equivalents	$	2,588	$	—	$	—	$	2,588
Trade accounts receivable		380		—		—		380
Trade accounts receivable - related party		643		—		—		643
Short-term investments		334		—		—		334
	$	3,945	$	—	$	—	$	3,945
Liabilities:
Warrant liability - related party	$	—	$	—	$	976	$	976
Warrant liability		—		—		922		922
	$	—	$	—	$	1,898	$	1,898

The Company’s cash equivalents, comprised principally of U.S. treasury securities, are classified within Level 1 of the fair value hierarchy.

The Company’s trade accounts receivable are classified within Level 1 of the fair value hierarchy and are related to the oxide plant lease per the terms of the lease rates established in the plant lease agreement.

At December 31, 2016, the Company recorded a liability for warrants to acquire the Company’s stock as a result of anti-dilution clauses in the warrant agreements that could result in a resetting of the warrant exercise price in the event the Company were to issue additional shares of its common stock in a future transaction at a price lower than the current exercise price of the warrants (see Note 15). The Company assesses the fair value of its warrant liability at the end of each reporting period, with changes in the value recorded as “Warrant derivative (loss) gain” on the Company’s Condensed Consolidated Statements of Operations and Comprehensive Loss. The valuation policies are approved by the Chief Financial Officer who reviews and approves the inputs used in the fair value calculations and the changes in fair value measurements from period to period for reasonableness. Fair value measurements are discussed with the Company’s Chief Executive Officer, as deemed appropriate. The warrant liability had been recorded at fair value as of December 31, 2016 based primarily on a valuation performed by a third party expert using a Monte Carlo simulation, which falls within Level 3 of the fair value hierarchy. The valuation model takes into account the probability that the Company could issue additional shares in a future transaction at a lower price than the current exercise price of the warrants. The Company did not have a warrant liability at December 31, 2017 as the result of a change in accounting principal during the period as discussed in Note 3.

The beneficial conversion feature of the Sentient Note represents an embedded derivative as defined by ASC 815 (see Note 10). ASC 815 provides that a derivative instrument’s fair value must be bifurcated from the host contract and separately recorded on the Company’s Condensed Consolidated Balance Sheets. At December 31, 2015 and at each of the conversion dates (see Note 10), the Company had recorded a derivative liability related to the beneficial conversion feature of the Sentient Note. On June 10, 2016, the remaining Sentient Note and related embedded derivative had been fully retired. The Company assesses the fair value of the derivative liability at the end of each reporting period, with changes in the value recorded as “Derivative loss” on the Company’s Condensed Consolidated Statements of Operations and Comprehensive Loss. The valuation policies are approved by the Chief Financial Officer who reviews and approves the inputs used in the fair value calculations and the changes in fair value measurements from period to period for reasonableness. Fair value measurements are discussed with the Company’s Chief Executive Officer, as deemed appropriate. The derivative liability was recorded at fair value at December 31, 2015 and each of the conversion dates based primarily on a valuation performed by a third party expert using a Monte Carlo simulation, which falls within Level 3 of the fair value hierarchy. The valuation model takes into account, among other items: 1) the probability of successfully achieving stockholder approval of the loan’s conversion feature, 2) future variations in the Company’s stock price, and 3) the probability of entering into an equity transaction prior to the Loan maturity date that would lower the conversion price.

In addition to the warrant exercise prices (see Note 15) and Sentient Note conversion price (see Note 10) other significant inputs to the warrant valuation model and derivative valuation model included the following as applicable:



	December 31,
	2016
Company's ending stock price	$	0.58
Company's stock volatility		110%
Applicable risk free interest rate		1.39%

An increase or decrease in the Company’s stock price, in isolation, would result in a relatively lower or higher fair value measurement respectively. A decrease in the probability of the issuance of additional common stock at a lower price than the current warrant exercise price would result in a lower value for the warrants. The table below highlights the change in fair value of the warrant liability and the derivative liability.


		Fair Value Measurements
		Using Significant Unobservable
		Inputs (Level 3)
	Warrant Liabilities
	(in thousands)
Ending balance at December 31, 2015	$	1,898
Change in estimated fair value		(364)
Ending balance at December 31, 2016	$	1,534

At December 31, 2017, the remaining warrants are recorded as equity as the result of a change in accounting principal as fully detailed in Note 3.

Non-recurring Fair Value Measurements

There were no non-recurring fair value measurements at December 31, 2017 or December 31, 2016.

The Company assesses the fair value of its long lived assets if circumstances indicate a change in the fair value has occurred. The valuation policies are approved by the Chief Financial Officer who reviews and approves the inputs used in the fair value calculations and the changes in fair value measurements from period to period for reasonableness. Fair value measurements are discussed with the Company’s Chief Executive Officer, as deemed appropriate.

No fair value adjustments to long lived assets were recorded during the years ended December 31, 2017 and December 31, 2016.